Please print out or copy this page to Notepad. Make sure to work through the fixes in the exact order it is mentioned below. If there's anything that you don't understand, ask your question(s) before proceeding with the fixes. You should 'not' have any open browsers when you are following the procedures below.
Go to My Computer->Tools/View->Folder Options->View tab and make sure that 'Show hidden files and folders' (or 'Show all files') is enabled. Also make sure that 'Display the contents of system folders' is checked. If you have Windows XP, the search feature is a little different. When you click on 'All files and folders' on the left pane, click on the 'More advanced options' at the bottom. Make sure that 'Search system folders', 'Search hidden files and folders', and 'Search subfolders' are checked.
For the options that you checked/enabled earlier, you may uncheck them after your log is clean. If we ask you to fix a program that you use or want to keep, please post back saying that (we don't know every program that exists, so we may tell you to delete a program that we think is bad to keep).
Reboot into Safe Mode by hitting the F8 key repeatedly until a menu shows up (and choose Safe Mode from the list). In some systems, this may be the F5 key, so try that if F8 doesn't work. Make sure to close any open browsers. Run a scan in HijackThis. Check each of the following and hit 'Fix checked' (after checking them) if they still exist (make sure not to miss any):
F2 - REG:system.ini: Shell=Explorer.exe C:\WINDOWS\userint32.exe
O4 - HKLM\..\Run: [Windows Service Manager] C:\WINDOWS\userint32.exe
Delete the following Files/Folders (delete folders if no filename is specified) according to their directory (if none, just do a search for them) and delete them if they exist:
C:\WINDOWS\userint32.exe - make sure you delete this exact file in this folder
Reboot into Normal Mode run a new HijackThis scan. Save the log file and post it here.
Let's use a program to scan for any trojans that may exist. Download TDS-3
http://tds.diamondcs.com.au/index.php?page=download. Learn how to use it at
http://tds.diamondcs.com.au/index.php?page=easytouse. Make sure to update it after you installed it. You can get the manual updates at
http://tds.diamondcs.com.au/index.php?page=update. When you launch the program, it will scan your memory for running processes. This will take less than 30 seconds. Next go to 'System Testing' on the menu and choose 'Full System Scan'. After that's finished, post the log file by selecting everything on the top pane (select from bottom to top). If any alarms are found, it will be listed in the bottom window. Please copy and paste that here also if it applies. If you have problems copying the text, look (or search) for a file named scandump.txt and see if that has the alarms - post that here.