Browser hijacked

Must be some your FF add-ons.

Start Firefox normally.
Disable all add-ons, but one.
Restart FF.
No problem?
Re-enable next add-on.
Restart....and so on until you'll find the culprit.

You sure can.
Check redirection issue BEFORE you install any new add-ons.

Good news

You can reinstall AVG now.

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 to its own folder

• Run JavaRa.exe (Vista 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.

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Last scans....

1. Download Security Check from HERE, and save it to your Desktop.

• Double-click SecurityCheck.exe
• Follow the onscreen instructions inside of the black box.
• A Notepad document should open automatically called checkup.txt; please post the contents of that document.
  
  NOTE SecurityCheck may produce some false warning(s), so leave the results reading to me.

2. Download Temp File Cleaner (TFC)

• Double click on TFC.exe to run the program.
• Click on Start button to begin cleaning process.
• TFC will close all running programs, and it may ask you to restart computer.

3. Please run a free online scan with the ESET Online Scanner

• Disable your antivirus program
• Tick the box next to YES, I accept the Terms of Use
• Click Start
• Accept any security warnings from your browser.
• Check Scan archives
• Click Start
• ESET will then download updates for itself, install itself, and begin scanning your computer. Please be patient as this can take some time.
• When the scan completes, push List of found threats
• Click on Export to text file , and save the file to your desktop using a unique name, such as ESETScan. Include the contents of this report in your next reply.
• NOTE. If Eset won't find any threats, it won't produce any log.

Looks good

...and Eset....

Your computer is clean

1. We need to reset system restore to prevent your computer from being accidentally reinfected by using some old restore point(s). We'll create fresh, clean restore point, using following OTL script:

Run OTL

• Under the Custom Scans/Fixes box at the bottom, paste in the following:

Code:

:OTL
:Commands
[purity]
[emptytemp]
[EMPTYFLASH]
[CLEARALLRESTOREPOINTS]
[Reboot]

• Then click the Run Fix button at the top
• Let the program run unhindered, reboot the PC when it is done
• Post resulting log.

2. Now, we'll remove all tools, we used during our cleaning process

Clean up with OTL:

• Double-click OTL.exe to start the program.
• Close all other programs apart from OTL as this step will require a reboot
• On the OTL main screen, press the CLEANUP button
• Say Yes to the prompt and then allow the program to reboot your computer.

If you still have any tools or logs leftover on your computer you can go ahead and delete those off of your computer now.

3. Make sure, Windows Updates are current.

4. If any Trojan was listed among your infection(s), make sure, you change all of your on-line important passwords (bank account(s), secured web sites, etc.) immediately!

5. Download, and install WOT (Web OF Trust): http://www.mywot.com/. It'll warn you (in most cases) about dangerous web sites.

6. Run Malwarebytes "Quick scan" once in a while to assure safety of your computer.

7. Run Temporary File Cleaner (TFC) weekly.

8. Download and install Secunia Personal Software Inspector (PSI): http://secunia.com/vulnerability_scanning/personal/. The Secunia PSI is a FREE security tool designed to detect vulnerable and out-dated programs and plug-ins which expose your PC to attacks. Run it weekly.

9. (optional) If you want to keep all your programs up to date, download and install FileHippo Update Checker.
The Update Checker will scan your computer for installed software, check the versions and then send this information to FileHippo.com to see if there are any newer releases.

10. (Windows XP only) Run defrag at your convenience.

11. When installing\updating ANY program, make sure you always select "Custom " installation, so you can UN-check any possible "drive-by-install" (foistware), like toolbars etc., which may try to install along with the legitimate program. Do NOT click "Next" button without looking at any given page.

12. Read How did I get infected?, With steps so it does not happen again!: http://www.bleepingcomputer.com/forums/topic2520.html

13. Please, let me know, how your computer is doing.

No...........

The issue seems to be resolved.