You likely don't have a virus. Very few windows users get virus's these days. What people get infected with is 'malware' .... The anti-virus software is next to useless these days and can be simply replaced with 1. common sense and 2. malwarebytes anti-malware.
* optional - boot into safemode
1) Download the free version and install.
https://www.malwarebytes.org/mwb-download/
2) Let it update.
3) Scan.
4) Remove the malware.
Simples.
Actually, anti-virus softwares nowadays also have anti-malwares, so if he's already had anti-virus (Avast is one of the best), there is no need to install another anti-malwares.
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You can try to refresh it.
http://windows.microsoft.com/en-us/windows-8/restore-refresh-reset-pc
I wonder if eventviewer would tell him why the apps are closing.
I don't have FF installed on my Surface, but you can check to see if FF is set to run when the computer boots, I know Chrome is set to, plus Windows tries to be helpful and reopen some applications if they were open on reboot.
The startup items are listed in Task Manager now and you can disable them from there.
Ok i downloaded the Malwarebytes and it scanned and at the end it did not find any viruses or anything like that and it actually made ALL of my Windows (even the default)metro apps stop working and immediately closes and goes back to the start sceen Now i can't use the video player Windows Metro app because of this!!!!
And every time i boot up and open Firefox it keeps asking me to choose Firefox as your default browser and i keep saying yes but it keeps happening.
And sometimes when i boot up my Windows 8 tablets there is a cursor in the of the sceen and before the User login sceen it goes away and i have not have my USB mouse plugged when i see it.
And it is becoming slower everyday opening firefox and other apps are not loading not as fast anymore and when i do a task it lags for about 2 seconds and it proceeds to do the task, it is annoying sometimes especailly when i do some video editing/making Youtube videos.. :/
What should i do?? Should i factory reset my Windows 8 tablet again or not?? I don't really want to do that again....
I really don't know what to do..... :/ :/