Cannot install (all sorts of) programs on Windows 7

[BlueStripe_99]

Hi,
A few days ago I uninstalled AVG from my computer to install my new antivirus software ESET. But when I installed ESET Smart Security 6 I got a message that the installation was interrupted before it was done. No error code... After that I tried installing Microsoft Word 2007 and here I got an error code too. I tried updating via windows update and even here I'm getting error codes for some updates. And even when I wanted to put AVG back on my pc. You already guessed what. Error code 0xC0070643. I have no idea what to do I think it might be a virus or a bad system file but have no idea what to do now. Any ideas?

EDIT: I CAN install MS Security Essentials and are now scanning my pc. There is hope

EDIT: Nothing found, still can't install ESET....

 

[RealBeast]

Some registry keys might have gotten messed up with the ESET install attempt. Can you restore to a point before that? If not, try running a system repair using your install disk.

 

[RealBeast]

Some registry keys might have gotten messed up with the ESET install attempt. Can you restore to a point before that? If not, try running a system repair using your install disk.