We should check if there are still some nasties hiding there, as there are many nasties that hides from the hijackthis scan.
You can run one of those online virus scanners, either BitDefender, TrendMicro or ActiveScan to see if they find something.

Or try Combofix.(use at your own risk)
Please download ComboFix by sUBs:
http://download.bleepingcomputer.com/sUBs/ComboFix.exe


You must download it to and run it from your Desktop
Now STOP all your monitoring programs (Antivirus/Antispyware, Guards and Shields) as they could easily interfere with ComboFix.
Double click combofix.exe & follow the prompts.
When finished, it will produce a log. Please save that log and attach it in your next reply.
Re-enable all the programs that were disabled during the running of ComboFix..


Note:
Do not mouse-click combofix's window while it is running. That may cause it to stall.

CF disconnects your machine from the internet. The connection is automatically restored before CF completes its run. If CF runs into difficulty and terminates prematurely, the connection can be manually restored by restarting your machine.