I am guessing you are  on MAS90 C/S v4.12.  As for the error message you are getting, this is why you should upgrade.  Note that almost everything you are running is not supported. From your level of MAS90 to your Windows OS. At some point you are going to have to bit the bullet and upgrade to get rid of the error conditions.

MAS90 is being maintained for archival and auditing purposes only. Sorry, but I cannot justify an upgrade at this time.

It does need to run though. If Win 7 end of support weren't coming up, it wouldn't be an issue as it has been running just fine until now. But I do need to keep it running for a few months longer, so I need to get it running on Win 8.1 or Win 10.

Any help would be greatly appreciated.

I've been collecting this info since I started working at Best Software back in '02. That was when 3.71 was shiny and new. I'm going to try to insert this as a picture, which I'm culling from my "PVXWIN32 Version Chart.xls". I'm guessing you are looking at an old 3.5 or 3.51 system (as there's a gap there in my chart). Wow! That's old. You are extremely lucky it will even run on Win 7.

If you can actually get this system to run, your best bet is to try to export as much data as you possibly can because one of these days, probably very soon, you will not be able to do anything with this program.

KB 29113 is in the KnowledgeBase. I don't know much about what Sage gates and what they don't gate these days but it seems odd to me you can post here on Sage City but not access the KnowledgeBase. Regardless, here is the text, such as it is:

Error: "Exception EAccessViolation in module ntdll.dll at 0001A1C1". Access violation at address 7C81A1C1 in module 'ntdll.dll'. Write of address 0149EEE8 after opening Sage 100 ERP

Disable Partner Enhancement Program (PEP)

1. Log into Sage 100 ERP as administrator
2. Disable Product Enhancement Program (PEP)

ID:29113Last Modified Date:6-10-2019  

Thank you for your reply.

This time I was able to get past the login screen (Hold that thought, more about that in a moment...)

Help / About displays this:

MAS 90
Version 3.41
Copyright 1996-1998 Sage Software, Inc.

It's the version that was corrected for Y2K, so I am told by long time staff.

I'm sorry, but I am logging in as an Administrator, and I do not see an Administrative Tools menu from which to disable PEP, nor do I see any mention of PEP in the other menu selections.

So this is what's happening when running MAS90 workstation on anything above Win 7 Pro:

After I enter the username and password in the login box, one of 3 things happens:

a) it works perfectly,

b) it stalls indefinitely as soon as I click OK on the login screen (the OK button will actually stay depressed and not pop back out), or

c) the main window comes up, blank, followed by the aforementioned "Access violation at address 0044FF7E in module 'launch32.exe'. Read of address 00000134" (on Win 8.1.)

And all this on the same 8.1 workstation. Repeat, on the same workstation.

Sunspots? Phases of the moon? It's maddening.

SMBv2 is turned off, and SMBv1 Server is on, on the workstation, otherwise it would not work at all and stall all the time. (b) above. 

Folks, this is a situation not of my choosing, please keep this in mind. Again, the goal is just to keep it running for archival and auditing purposes.

Thank you so much for your help.

If you can get ODBC running, query every table and store elsewhere (MS Access, Excel, SQL...).  Then you have the data, and don't need to run the program.

I think you're looking at an exercise in futility trying to get this old software to run on new platforms. In fact I'm surprised it runs on Win 7. That being said, if Kevin M's suggestion doesn't work, my final thoughts on this are:
A. Perhaps you should spin up a virtual machine with Win 7 and don't put it on the Internet or update it - just keep it around, as you say, for archival purposes.
B. Maybe you could run it in a Compatibility Mode, although I'm guessing you'll have already tried that.
C. You might try to get your hands on a 3.71 installation "disk" and try to get it up to that level. It might migrate and convert. I can actually open up my MAS 90 3.71 on my Win 10 laptop - although I'm going straight through the PVXWIN32. I wouldn't try to actually run the installation program.

Well heck, if all you are doing is maintaining for archival and auditing then dump everything into either Access or SQL. 

I think I may have stumbled on a "fix".

As you may know, DLL and VB control conflicts are an age-old problem with Windows. MAS90, being ancient, installs ancient controls and DLL's.

We have another application on some of our workstations, let's call it "D". Current and supported.

I recall that I once installed "D" on a workstation, tested it, and then installed MAS90 after that. Big mistake. MAS90 broke "D", Did a reinstall of "D", and it worked. So obviously MAS90 and "D" share some controls or DLL's. MAS90 broke "D" by replacing the newer controls with the ancient ones.

So I got an idea. Would installing "D" after MAS90 fix MAS90?

Well... maybe. Like I said, the problem is intermittent. Would have to test it thoroughly to find out.

Makes sense though...

And the answer is... a partial fix.

The indefinite stall after pressing the OK button seems to be gone.

The access violation error is not. But it's now about 1 in 10 logins instead of 1 in 3 or 4.

And the answer is... a partial fix.

The indefinite stall after pressing the OK button seems to be gone.

The access violation error is not. But it's now about 1 in 10 logins instead of 1 in 3 or 4.