Could you please help with this computer question?

It may be worth while for both you and your sister to scan your computers entire hard disk(s) in case an infection was transferred to your computer from her computer via the flash drive (USB stick/pen). The flash drive itself should also be plugged into one of the computer's and scanned.

Try this:

Firstly, boot your computer to the Safe Mode menu screen. You do this by repeatedly pressing F8 as soon as you boot up. Once there, use the arrow keys to highlight Safe Mode with Networking. Continue to boot from there, by pressing Enter. You will now see some drivers being loaded. There will be a pause at some point. This usually lasts for no more than 30 seconds.

If that's successful, download and run TDSSKiller.exe from Kaspersky Lab. It's tiny, and takes just a minute to run. It hunts down and kills a specific family of rootkits:

http://support.kaspersky.com/faq/?qid=208280684

Regardless of the results, download the free version of Malwarebytes' Anti-Malware (MBAM). Install it, get updates and run a full scan (still in Safe Mode). This is a direct download link. Copy and paste it into your browser’s address bar, and press Enter.

http://www.myantispyware.com/mbam

After this, try rebooting normally. If that's successful, I recommend you run another full scan with MBAM. It will detect malware that wasn't running in Safe Mode.

You should now delete TDSSKiller.exe, as updated versions are often made available. Malwarebytes' Anti-Malware can be easily uninstalled, should you wish to do so, but it may prove to be beneficial in the future.

On a related note...

You could download Open Office or Libre Office. Both are free, and I may be wrong, but I believe both can access documents created in Microsoft Office.

You will see on this download link that as of April 2011, development of Open Office has been terminated. I'm not sure that's true, as it was purchased and renamed Apache Open Office...and this latest version is dated 10th May, 2012.

http://www.filehippo.com/download_openoffice/

Now for Libre Office:

http://www.filehippo.com/download_libreoffice/

This link may prove useful, if you decide to download Libre Office:

http://www.libreoffice.org/get-help/installation/w...

Hope this helps.

Do a scan with malwarebytes: http://www.malwarebytes.org/

You could have caught something off your sisters laptop.

Norton is rubbish, buy kaspersky (the best and under £20 on amazon)

You should download open office for opening Microsoft files for free: http://www.openoffice.org/

Firstly go to the internet café or a friend's house to send the CV. Then use MalwareBytes to scan your entire computer for viruses/malware. If that does not work, then try a normal System Restore.

Is it opening webpages as a text documents?

Check the default program for opening webpages - it should be a browser like Internet Explorer instead of a text editor like NotePad or WordPad.