I guess that depends on what changes you make, and if you mess-up your registry, or your profile. If you performa a FULL reinstall, and the problems are no longer present, then you've most likely corrected the mistakes made by altering files.
If you still have problems after a reinstall, it could be difficult to determine the exact cause, this is why we suggest that you don't alter anything like that
Regards.
DJM/Carl.