I uninstalled 4.5 and installed 2.0 and still nothing 🙁 I went through my entire SLRR and computer to see if I had accidentally made a copy of resconvert or resdecode and could't find anything.
Also, I opened both decode and convert and this is what they said. This is the first time I've opened them so I don't know if this is normal.

Added 7 days later:
Small update on this, I've noticed on some cars I don't have this problem. If I do it on the '66 Nova, it works every time, but on the majority of all my other cars I get this error. If that helps at all.