First thing you need to do is download a program called Hijackthis.
Hijackthis
"Do a system scan and save the log file" The log file will open in notepad.
Click FILE "Save As" and save it somewhere you will remember. Now go to the link below.
http://www.hijackthis.de/
(DO NOT CLOSE HIJACKTHIS PROGRAM!)
This is a Hijackthis Log analyzer site. Click "Browse" and find your log file you saved on your computer. Click "Open" Then "Analyze" The program will now search out any bad startup files or malware that should not be starting up with your computer. Once its done, there will either be a Green checkmark next to a file that is good, or a red X next to a file if it is bad. Make sure you read descriptions before you make changes to things. Now once you start finding things you do not like from the results. you will want to take notice to the R1, R0,02 numbers before the file paths. If R1 is the file that they deem "NASTY" then you will want to go back to the actual Hijackthis program and check the corresponding box of the same number and letter. IE R1 on the site and R1 on the program.
Once you are done finding all the "Nasty" problem files, click "Fix Checked"
you may require a restart after this but this concludes using hijackthis.
Next go to download.com and install Avast Antivirus free edition
http://download.cnet.com/Avast-Home-Edition-Free-Antivirus/3000-2239_4-10019223.html
. It has a boot time virus scan. to enable boot time scan do the following.
To schedule boot scan using Avast, follow the steps below:-
* Right click on the Avast system tray icon
* Click on “Start Avast Anti Virus”
* Avast anti virus window will pop up and run a memory scan
* Once memory scan finish, you can right click on the Avast anti virus window and select “Schedule Boot Time Scan”
* “Schedule Boot Time Scan” window will popup, select “Scan all local disk” and check on “Advanced Options”
* For normal infected file select “Move infected files to Chest” and select “No action” for system files and Press “Schedule” button.
* Avast will prompt you for restart to perform the Boot time scan and click “Yes” to reboot and start the scan.
* Done you have just scheduled a boot time scan from Avast anti virus
One you are done removing virus's you should download superantispyware to remove the spyware and most of the malware.
http://download.cnet.com/SuperAntiSpyware-Free-Edition/3000-8022_4-10523889.html?tag=mncol
after you have done all of this the last thing to do would be to run a defrag on your computer. I would go with a good program such as O&O defrag or something along those lines. Well let me know how it runs after this and good luck!
Ya reformatting sometimes is the answer but its not always necessary.