Trojan.BHO removed but internet explorer and options issues

Go ahead with Eset scan and we'll go back to IE issue after that.

Very well.

Update Adobe Flash Player: http://get.adobe.com/flashplayer/
Make sure you UN-check Yes, install McAfee Security Scan Plus

NOTE 1: Beginning with Adobe Flash Version 11.3, the universal installer includes the 32-bit and 64-bit versions of the Flash Player.
NOTE 2: While installing make sure you UN-check any extra garbage which wants to install alongside.

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Update Adobe Reader

You can download it from http://www.adobe.com/products/acrobat/readstep2.html
After installing the latest Adobe Reader, uninstall all previous versions (if present).
Note. If you already have Adobe Photoshop® Album Starter Edition installed or do not wish to have it installed UNcheck the box which says Also Download Adobe Photoshop® Album Starter Edition.

Alternatively, you can uninstall Adobe Reader (33.5 MB), download and install Foxit PDF Reader(3.5MB) from HERE.
It's a much smaller file to download and uses a lot less resources than Adobe Reader.
Note: When installing FoxitReader, make sure to UN-check any pre-checked toolbar, or any other garbage.

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1. Update your Java version here: http://www.java.com/en/download/installed.jsp

Note 1: UNCHECK any pre-checked toolbar and/or software offered with the Java update. The pre-checked toolbars/software are not part of the Java update.

Note 2: The Java Quick Starter (JQS.exe) adds a service to improve the initial startup time of Java applets and applications. If you don't want to run another extra service, go to Start > Control Panel > Java > Advanced > Miscellaneous and uncheck the box for Java Quick Starter. Click OK and restart your computer.

2. Now, we need to remove old Java version and its remnants...

Download JavaRa to your desktop and unzip it.

• Run JavaRa.exe (Vista and 7 users! Right click on JavaRa.exe, click Run As Administrator), pick the language of your choice and click Select. Then click Remove Older Versions.
• Accept any prompts.
• Do NOT post JavaRa log.

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Now....

Download Windows Repair (all in one) from this site

Install the program then run it.

Go to Step 2 and allow it to run CheckDisk by clicking on Do It button:





Once that is done then go to Step 3 and allow it to run System File Check by clicking on Do It button:




Go to Step 4 and under "System Restore" click on Create button:




Go to Start Repairs tab and click Start button.




Please ensure that ONLY items seen in the image below are ticked as indicated (they're all checked by default):



Click on box next to the Restart System when Finished. Then click on Start.

See if it fixes your original issue.

Skip it for now.

The above error may be connected to your original issue.
Something in Windows installation is messed up.

The only other thing can suggest would be repair installation: http://www.vistax64.com/tutorials/88236-repair-install-vista.html

Install Panda USB Vaccine, or BitDefender’s USB Immunizer on your computer to protect it from any infected USB device.

Plugin your external drive and scan it with your AV program.

You're very welcome