Spine's launcher is 64-bit. Spine editor versions below 4.0 are 32-bit. If you choose a version < 4.0 then when you click Start the launcher starts a different executable, launcher\1\Spine-1.exe, which is a 32-bit program. Have you also excluded that executable from the antivirus and similar software?
Your log shows a VerifyError when Spine tries to read some of its files, meaning it found the files to be invalid. The files are stored in the C:\Users\brodee\Spine\updates\3.8.99 update file, so if something modified that file it could cause this problem.
The launcher deleted the 3.8.99 file and downloaded a new one. It then ran the 3.8.99 editor and got the other error, EXCEPTION_ACCESS_VIOLATION, which just means something terrible happened (memory was accessed where it shouldn't be). Unfortunately there are many reasons that could happen, so this doesn't provide any clues.
That it works sometimes is strange. My best guess is that something modifies Spine's files on your computer. Do you prevent your antivirus from messing with C:\Users\brodee\Spine\updates\? I suggest removing the antivirus completely (not just disabling) to see if it is the cause.
