hmm, very odd
cant say that i've ever hurd of anyone having such a problem.
if you wouldnt mind lets try a few things as tests to see what happens, maybe that will give me (or someone else) an idea on what might be the trouble.
First, in mIRC press down and hold the ALT key, then type the leter o then release both keys (ALT+O)
this 'should' bring up the mirc options dialog, does it?
if so, select a common server and try to connect, if you cant connect please show us the error you get for the reason as to why you cant connect.
as far as a list of files mirc instals, all files that mirc instals are instaled into the directory where the mirc.exe program file is located, (to the best of my knowledge), there are a few registry keys that are added to the windows system registry but none of which should affect whats happening to you.
please try your best to suply us with a few more details regarding this problem so that we can beter address it
Cobra^
