Many programs refuse to run with APPRCRASH/wininet.dll errors.

Recently my computer had a blue screen of death. When it restarted, a variety of programs failed to boot properly, merely giving a "has stopped working" error when they attempt to load. The contents of these error messages are similar; here's one:

Problem signature:
Problem Event Name: APPCRASH
Application Name: iTunes.exe
Application Version: 11.0.2.25
Application Timestamp: 5122bf96
Fault Module Name: WININET.dll
Fault Module Version: 10.0.9200.16521
Fault Module Timestamp: 51207800
Exception Code: c0000005
Exception Offset: 00142147
OS Version: 6.1.7601.2.1.0.256.1
Locale ID: 1033
Additional Information 1: 0a9e
Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
Additional Information 3: 0a9e
Additional Information 4: 0a9e372d3b4ad19135b953a78882e789

My web browsers either don't work or crash if I try to download any files. Does anyone have an idea what's going on with my computer?

I had to boot into HP's system recovery mode to do a system restore, and I was able to restore to before this started; it didn't solve the problem. Startup repair found no problem either.

If I run a System Restore from within Windows, it starts properly and goes to the blue, system restoring screen, but at some point it fails before it actually restores and my laptop tries to boot into repair mode. I have Microsoft Security Essentials and it's up to date and hasn't found any problems. I ran a scan with Spybot S&D and it didn't seem to turn up any problems either. I'll run a scan with Malwarebytes. I'll need to download it on another computer: Chrome crashes when I try to download a file, and Firefox and IE 10 don't run at all--they just give the "has stopped working" error, and Firefox has the Mozilla crash report tool pop up too.

No, it came with home premium and I upgraded it to ultimate when I first got it.

Through my university; I got a disc and a license key and used the key to upgrade.