Notepad icon goes missing.

Hi there,
I recently installed a software on my pc and the notepad icon was
automatically replaced by a 'printer' icon. There are some other icons like
the zipped file folder icon whcih were automatically replaced by another
icons. I know that this may have occured due to a problem with the
shell32.dll file or imageres.dll file, however how do I repair /replace
these. I do have an orginal Vista dvd and I tried looking for these files on
it so that I could replace them with those, but I could not find them.

A system restore, i know would help, but the restore point on my pc is
pretty recent and it wont help.
Please help.
Thanks.