Internet explorer removal or update ?

So, I helped to hose my co-workers machine.

She had tried removing ie-7 before and it wouldn't let her revert back to it. And i tried too, I removed all registry entries about IE and then tried and nothing...

this also made her outlook fail to open. Now, IE is so stupid, that it does not update at all... can't remove it... can't install another version.

the version that opens says version : 0 and then if you try certain thigns it says you need at least 5.0 but then when you try to install 6.0 it says a higher version is installed.

try installing 7.0, it fails and prompts you to restart the system... any help would be appreciated.