If Flash isn't installed, it's probably not Flash that's the problem. The only thing we did was write some files to our own little encapsulated area. If the disk was in a bad state, something bad might have happened when the OS wrote those files, but that's all happening below us.
If it was me, I'd start here.
Check your hard disk for errors - Windows 7:
https://support.microsoft.com/en-us/kb/2641432
If everything comes back clean, you might run a manual scan of the registry (a backup is always a prudent idea before you mess with the registry):
https://support.microsoft.com/en-us/kb/183887
After that, I'd start looking at a virus scanner and an anti-malware tool. malwarebytes.org is free and well-respected.
It's also possible that something upstream from you is causing your internet connection to be really slow. It sounds like you're familiar enough with this stuff to do some network troubleshooting without guidance.
It's alright, I fixed it!
I just installed Java and uninstalled Adobe!