Well it is very odd indeed.
You might have incompatible add-ons:
Go to Start | All Programs | Accessories | System Tools
and click Internet Explorer (No Add-ons).
You can also try resetting IE
Tools | Internet Options | Advanced
Scroll to the bottom and click Reset Internet Explorer Settings
Note that the Reset IE Settings button will delete AutoComplete data (such
as passwords.) so be sure you have those backed up.
IF your copy of IE7 is an update from the previous version...IE6, you CAN roll back to the previous version, since you have not yet applied the XP SP3 update(this is one reason for not doing so by the way). Go to Start, Control Panel, Add/Remove and Uninstall IE7, this will then roll you back to IE6.

Or it could be malware that has not been found by the scans you have done thus far.


Tell you what, I would like you to try a scan with combofix...very similar to the DSS scanner that you all ready ran but without the HJT connected to it. Just want to see if same results show and it will do some fixing if something is found by the program.
download Combofix
to the desktop.
When you have the Save as screen configured to save ComboFix.exe to the Desktop, click on the Save button. ComboFix will now start downloading to your computer.
Double-click on the ComboFix icon found on your desktop. You will be asked if you are sure you want to run the program. Click the RUN button. Follow any prompts given and be sure to agree to the disclaimer. Please note, that once you start ComboFix you should not click anywhere on the ComboFix window as it can cause the program to stall. In fact, when ComboFix is running, do not touch your computer at all and just take a break as it may take a while for it to complete.Be aware that ComboFix will disconnect your computer from the Internet. Therefore, do not be surprised or concerned if you receive any warnings stating that you are no longer on the Internet as your connection will be completely restored at a later stage in the program.
ComboFix will now start scanning your computer for known infections. This procedure can take some time, so please be patient.
While the program is scanning your computer, it will change your clock format, so do not be concerned when you see this happen. When ComboFix is finished it will restore your clock settings to what they were previously. You will also see the text in the ComboFix window being updated as it goes through the various stages of its scan.
When ComboFix has finished running, you will see a screen stating that it is preparing the log report.
This can take a while, so please be patient. If you see your Windows desktop disappear, do not worry. This is normal and ComboFix will restore your desktop before it is finished. Eventually you will see a new screen that states the program is almost finished and telling you the programs log file, or report, will be located at C:\ComboFix.txt.
When ComboFix has finished, it will automatically close the program and change your clock back to its original format. It will then display the log file automatically.
Note:

Do not mouseclick combofix's window while it is running. That may cause it to stall.

When all is complete post back here with the combofix log.