Now that you're able to boot in Normal Mode, why don't we run some scans and see if we can find out what's happening?
Once I see the logs I can give you some advice on how to protect your computer.

Please do this: Hold CTRL, ALT and Delete all at once to bring up the taskmanager. In the Process tab click twice on the Memory Usage. That will list the highest to the lowest processes. Do a screen print and post it in your next reply
How to post screenshots or images

SUPERAntiSpyware

If you ALREADY have SUPERAntiSpyware be sure to check for updates before SCANNING!

Download SuperAntispyware Free Edition (SAS)
* Double-click the icon on your desktop to run the installer.
* When asked to Update the program definitions, click Yes
* If you encounter any problems while downloading the updates, manually download and unzip them from here
* Next click the Preferences button.

•Under Start-Up Options uncheck Start SUPERAntiSpyware when Windows starts
* Click the Scanning Control tab.
* Under Scanner Options make sure only the following are checked:

•Close browsers before scanning
•Scan for tracking cookies
•Terminate memory threats before quarantining
•Please LEAVE the others unchecked

•Click the Close button to leave the control center screen.

* On the main screen click Scan your computer
* On the left check the box for the drive you are scanning.
* On the right choose Perform Complete Scan
* Click Next to start the scan. Please be patient while it scans your computer.
* After the scan is complete a summary box will appear. Click OK
* Make sure everything in the white box has a check next to it, then click Next
* It will quarantine what it found and if it asks if you want to reboot, click Yes

•To retrieve the removal information please do the following:
•After reboot, double-click the SUPERAntiSpyware icon on your desktop.
•Click Preferences. Click the Statistics/Logs tab.

•Under Scanner Logs, double-click SUPERAntiSpyware Scan Log.

•It will open in your default text editor (preferably Notepad).
•SAVE the notepad file to your desktop by clicking (in notepad) File > Save As...

* Save the log somewhere you can easily find it. (normally the desktop)
* Click close and close again to exit the program.
*Copy and Paste the log in your post.
*********************************************
Download DDS from HERE or HERE and save it to your desktop.

Vista users right click on dds and select Run as administrator (you will receive a UAC prompt, please allow it)

* XP users Double click on dds to run it.
* If your antivirus or firewall try to block DDS then please allow it to run.
* When finished DDS will open two (2) logs.

1) DDS.txt
2) Attach.txt

* Save both logs to your desktop.
* Please copy and paste the entire contents of both logs in your next reply.

Note: DDS will instruct you to post the Attach.txt log as an attachment.
Please just post it as you would any other log by COPYING and pasting it into the reply.
thanks Dave i'll be back at my desktop computer tomorrow, so i'll follow your instructions and post results, thanks