SHELL.DLL is an important Windows System file. If this file is missing or 
corrupted, then this is due to a Trojan/Virus. While we are not able to assist
with the Windows Operating System we would suggest running a full virus scan 
and make sure you have the latest virus definition files installed. You may 
also wish to run some good Spyware detection software that detects and removes
Trojans. 

Even if this file IS found in your System, usually its size has been altered 
or corrupted by the virus. Therefore, replacement with a fresh copy would be
necessary. 
______________________________________________________________________________