Could be due to a parasite; what you describe is a typical symptom of that. You might want to try the following:
, download it to a folder you create for it on your C: drive. To create a folder on your hard drive, right-click "My Computer" from your desktop or Start panel, Select "Open", then find, select and open the folder for your C: drive, and from the toolbar in that folder, Select "File", then select "New", then click "Folder". When "New Folder" appears, give it a name you will recognize as the download you are about to perform and direct the download into that folder. Disconnect from the internet, then boot into Safe Mode[/i][/b]
. Find and open the CoolWebShredder folder, then click the icon to start it. Click "Fix" (not "Scan Only") and let it fix whatever it finds. When it has completed, reboot, and reconnect to the internet.
Without doing any other surfing, get AdAware Basic Before opening and installing AdAware, see: How to update AdAware
and AdAware Full Scan Instructions.
. With no other browser windows open or applications running, install AdAware. Once AdAware has been installed, updated, and configured to run at next boot (make sure its configured for a full scan per the earlier instructions ... also available also in AdAware's built in "Help" documentation), disconnect from the internet, and reboot. AdAware should launch before anything else. Let it fix whatever it finds.
Now, get, install, and configure Spybot S&D
. When the download has completed, close all browsers and running programs, and install SpyBot S&D. When the installation is complete, the program will open. Before running SpyBot, update it. Next, when it has updated, leave Spybot open, disconnect from the internet, then select "Immunize", and then select "Install" in the panel beneath, titled "Permanently Running bad download blocker for Internet Explorer. Do not check any of the boxes in the lower panel (Recommended miscellaneous protection") at this time. Now, while still disconnected from the internet and with no other browsers open or apps running, select "Search and Destroy", then select, at the bottom of that page, "Check for problems" (while it is running would be a good time to click on "Help", and read the tutorial). When that has finished, click "Select all items", then click "Fix selected items". As with AdAware, Spybot may ask to run again on next boot to fix some problems. Again, naturally, if so, grant it permission and reboot; if it does not, run it one more time anyway, then reboot.
When that has been done, reconnect to the internet and go immediately to Windows Update
and get any needed Critical Updates and any other security or privacy updates which may be recommended. While you're there, take a look at Microsoft: How to protect my computer
Make sure also you have a current and properly configured antivirus, and use at least XP's built in Firewall
Note: if you're not running XP, lemme know what OS you are using; there are some adjustments to be made in the above for other versions of Windows.