Unable to debug VS2017

I am having trouble simply getting VS2017 to run my program in debug mode. The program is a Windows Form Application. I was using it this morning to try to debug the code and it was working fine, except for the bug i was trying to track down, where the code exited without much warning. I was able to step through until the program exited.

The next time i tried to run the code in debug, the screen froze. When it finally recovered, i had this error:

'TRAP.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_64\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. Cannot find or open the PDB file.
The program '[10804] TRAP.exe' has exited with code -1073741818 (0xc0000006) 'In page error'.

It will work fine without debugging and other similar programs work fine with and without debugging.

I have tried:

1. Restarting the computer so there is nothing unexpected running in the background.

2. Re-installing VS2017 community Ed

3. Selecting "Microsoft Symbol Servers" from Tools->Options->Debugging->Symbols

   This resulted in this message box that seemed to freeze as well. I never saw any progress made on the progress bar. I cancelled it after about 20 min.

4. Setting <Optimize>false</Optimize> in the project file as suggested by Liam

5. Restarting the computer and trying again.

I was able to debug when i created another local repo on my home computer, so i tried re-cloning the repo at work and it has resolved the issue.

I did get an "Alert warning" message box:

Revocation information for the security certificate for this site is not available. Do you want to proceed?

After accepting the warning and proceeding, the application seemed to load the necessary PDB files and is working fine now.