Most frustrating problem ive come across...

One day i turn on the PC and Windows Live Messenger just refuses to open, it crashes upon opening. I just get the box that says program has encountered an error and has to close.
I then searched around, people said there is a registry fix, but the key did not exist in my situation.

Upon further investigation, i enabled the Guest account, i opened MSN and i got some more info.
APPCRASH
Caused by msvcr90.dll

Some googleing lead me to believe its to do with the Visual C++ Runtimes. So i removed all of them and reinstalled all of them from 2005 to 2008 x64 and x86.

Still the problem existed. Then i thought maybe its MSN being gay, so i got Trillian. To my surprise it didnt work either just crash upon startup, i found that it also had a reference to msvcr90.dll in its installation directory.

I also tried MSN versions 14.0.8050.1202 and the latest Live 2011 one, both dont work.

I just cannot figure this one out, anyone care to advise?

< Installed .NET Frameworks >
.NET FW 2.0 SP 2
.NET FW 3.0 SP 2
.NET FW 3.5 SP 1
.NET FW 4.0 Client


Specs:
Windows 7 Ultimate x64
i7 920
6Gb DDR3 1333Mhz
ATi 5850
SeaSonic 620W PSU

Nope, i have System restore disabled, in all my years of using PCs i haven't come a across of a problem i cant sort out, and im a safe browser, my AV has yet to detect anything so i never bother with it.

But i have managed to fix it.
I went into "Turn Windows Features On or Off", then i disabled .Net Environment and Microsoft .Net Framework 3.5.1, Reboot and MSN and Trillium work!

But with this component of Windows disabled am i going to run into more problems with different programs? And why does this fix it? Very weird.

Only thing to try is a repair install, also sfc /scannow says that it found problems, but cant be fixed, see the log, but i cannot make sense of the log, too much info.

Another thing, i put the .Net Environment and .Net Framework 3.5.1 back to enabled in Windows Features. As expected MSN and Trillian crash on open again.

But when they were disabled mw Moder Warfare 2 woudnt run, hence my reason to re-enable them, but now it crashes on open too, even though my PC is back to how it was originally.

Arghh driving me nuts, im at Uni so i dont even have my Windows Disk with me

Also another program thats not working, SMplayer, crash upon opening a file.

Im sure its all related as its all happened at the same time. Isnt there a way to completely remove .net Framework and reinstall it?

None of those removal things work, and cant reinstall .Net Framework as it reports i have to use the "Turn On or Off windows features" options.

Looking through sfc /scannow, these are the corrupt DLL's, though none have any relation to my problem from what i can tell.
OobeFldr.dll
gameux.dll
msdt.exe
SyncCenter.dll
NlsData0009.dll
QAGENT.DLL
netshell.dll
dfshim.dll
wdscore.dll
AcXtrnal.dll
cewmdm.dll
WMVENCOD.DLL
cewmdm.dll

Ok i manually mounted the install.wim from the DVD with imageX_x64 then got all the files from the DVD that are reported corrupted, i replaced all the files, then i opened MSN (without reboot) and it worked wooop!

I found msvcp90.dll in sfc /scannow log too, so i figured it must be the problem, after replacing it (and the others), everything seems to work!