NIS is not "all that". It's fine for AV in most cases, but it's not good with spyware. You need to scan with another because a locked homepage is not normal - unless it's locked by NIS, SpywareBlaster or another anti-malware program. You need to address this issue because you will get nowhere until you do.
We can't scan for you. You have to double-check yourself.
As I've said, she can get full function with Firefox in the meantime. Opera is another option.
The only other methods I know of fixing this problem are:
1. Reinstalling IE7
2. Repairing Windows
3. Reinstalling Windows
You may have to do one of those even if this is malware, but "first things first".
System Restore will restore the registry key, but it will not fix the homepage lock.