I'm running Sam 4.9.8 on Windows 7. It won't start. I get this error message:
Problem signature:
Problem Event Name: APPCRASH
Application Name: SAMBC.exe
Application Version: 1.0.0.0
Application Timestamp: 2a425e19
Fault Module Name: MSVCR80.dll_unloaded
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 4ca2b271
Exception Code: c0000005
Exception Offset: 650129e1
OS Version: 6.1.7601.2.1.0.768.3
Locale ID: 1033
Additional Information 1: 0a9e
Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
Additional Information 3: 0a9e
Additional Information 4: 0a9e372d3b4ad19135b953a78882e789

I disabled Norton, but that did not work. I rebooted. Not that either. I put MSVCR80.dll into C://Windows/System 32, and that didn't work.

What do I do?

It's not complaining about the Visual C++/C# aka .NET Runtime not being available at all, but about it being unloaded from memory.

Installing just the DLL is a bad idea, but often found as an "easy fix" on even reliable tech-news websites.
Doing so CAN fix the problem, but there's no way to tell if it really will help in advance, because the .NET Runtime is a lot more than just one DLL file.

On Windows 7 I think you still need to manually install .NET 2.0 from a redistributable package.
On Windows 8, 8.1 and 10 you can install .NET from the software and features menu in Windows Settings/Control panel (and I would strongly recommend doing it that way)

Running Windows 7 after January 2020 is a security risk and should be limited to Offline-only systems.

_________________
Benedikt Bauer - SVS (Spacial Volunteer Support)

Shop for readymade PAL scripts by countrywesterndj - Or get a custom script made by me (or others)

My Project:
Send "Now Playing" from SAM to Twitter and/or Facebook | Sourcecode

I run Windows 7 and Net 2.0 is already installed.

I meant to reinstall it/change/repair it.

_________________
Benedikt Bauer - SVS (Spacial Volunteer Support)

Shop for readymade PAL scripts by countrywesterndj - Or get a custom script made by me (or others)

My Project:
Send "Now Playing" from SAM to Twitter and/or Facebook | Sourcecode

I repaired Microsoft NET 4.5 (I did not see 2.0 in Programs), updated Windows 7, but SAM still won't boot up. There is a new error message, however:
Problem Event Name: APPCRASH
Application Name: SAMBC.exe
Application Version: 1.0.0.0
Application Timestamp: 2a425e19
Fault Module Name: MSVCR80.dll
Fault Module Version: 8.0.50727.4940
Fault Module Timestamp: 4ca2b271
Exception Code: c0000005
Exception Offset: 000029e1
OS Version: 6.1.7601.2.1.0.768.3
Locale ID: 1033

Since the error message still mentions that DLL, I thought perhaps it relates to the one I put in yesterday, so I removed it from Windows/System 32. Here is the new error message:

Problem Event Name: APPCRASH
Application Name: SAMBC.exe
Application Version: 1.0.0.0
Application Timestamp: 2a425e19
Fault Module Name: StackHash_abcc
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 00000000
Exception Code: c00000fd
Exception Offset: 7788b60a
OS Version: 6.1.7601.2.1.0.768.3
Locale ID: 1033
Additional Information 1: abcc
Additional Information 2: abcc8f7853b48d9807d6d51eb1fa5df9
Additional Information 3: abcc
Additional Information 4: abcc8f7853b48d9807d6d51eb1fa5df9

So I removed SAMBC.exe from DEP, and yet another error message:

Problem Event Name: APPCRASH
Application Name: SAMBC.exe
Application Version: 1.0.0.0
Application Timestamp: 2a425e19
Fault Module Name: unknown
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 00000000
Exception Code: c00000fd
Exception Offset: 7726b60a
OS Version: 6.1.7601.2.1.0.768.3
Locale ID: 1033