I will set all the issue first, then I will ask my questions.
first, I found many EXE files in many folders on my PC, I guess that I were attacked by a virus, I discovered that I fixed the kaspersky 5.0 before but I remove it because I didn't trust it, I found that many times this antiviruse were not able to resolve the problems with many PCs including my PC, it just give warnings, but unfortunatly and because of the time, I didn't install any other software.
after I discovered the exe files, which were with same name of some folders and files in my PC, I try to execute one of them to check what's the effect, I found the colors of desktop is changing and many other unexpected affects.
after that I restarted the PC, and I bought the norton antivirus 2006, I installed it, it cand discover the antivirus, it was (w32.rontokbro.b@mm) and it calssified it as a high risk anti virus, I go through the removal procedure but the virus was not rmoved, after 4 days I dicovered that at least one file on my pc was corrupted, and there were many file have some courrpted name with 1KB size, the virus still there. I decided to format the PC and install the anti virus again. now, my PC is stable.
in the removal procedure, I found that the virus changed some values in the registry key, changed in the group policy, and make more effects on my files, I found that most effects were on the share foloders, but the removal procedure said that this virus is coming often with e-mails.
any way, my partners have the same virus, I didn't make any share folders on my PC, but I want to resolve the problem on thire PC and also I want to have the most successful and effecint implementation of the PCs security.
so what to do with thier PCs if we don't want to format it, and we found that one PC was formatted but the virus appear again(the anti viurs was not activiated yet), so what's the solution? and what's the best effeicent anti virus now (what are the differnces?)? also what's the security procedures that we have to track in order to give maximum security to our systems.