Before going for HijackThis, its a good practice to perform preliminary steps to clean your PC. There are some very good tools to do this!
Download Ewido and install it. Then run, you will receive a warning message saying "Database not found", click "OK" for this. Next in the main screen, click "Update" and click "Start Update".
After the update process, click on the "Scanner" button in the left menu, then click on the "Complete System Scan" button.
If ewido finds anything, it will pop up a notification. You can select "Clean" and check the boxes "Perform action with all infections" and "Create encrypted backup" before clicking on OK.
When the scan finishes, click on "Save Report". This will create a text file.
Download CleanUp! and install it. Run it and click "Options.." button. Here move the "Quick Setup" slider to "Thorough Cleanup" position. Uncheck the option "Delete Favorites Palces/Bookmarks", if you have any bookmarks. Click "OK" to return to main window, and click "CleanUp!" to start cleaning. After it completes, click "Close" and click "No" to avoid logging off.
Finally, download HijackThis and unzip it to dedicated folder (like C:\HijackThisFolder\hijackthis.exe).
Then run it and click the button Do a System scan and save log file. HijackThis will perform a scan and saves the log file as hijackthis.log in the same folder where it is installed and it also opens the file automatically.
Copy the entire contents of the file and post it here along with the Ewido log.