You have to start pressinf F8 as soon as the computer starts booting - if you get to the screen which says Windows is loading you're too late.
When you do get the magic screen, choose safe mode with networking - that should let you get on line and download Malwarebytes.
If you really can't get to that option, download Malwarybytes on the desktop, put it on a USB stick and then install it from the stick onto your laptop. Ideally you should run it in safe mode because you will need to get teh latest updates before doing a scan, but if you really can't get into safe mode it won't hurt to try running it anyway.
If all else fails, use the desktop to download and burn the Avira rescue disk to CD, then use that to boot the laptop and let it run a scan. You can download it from
http://www.free-av.co...ir_rescue_system.html and a tutorial on using it is at
http://forum.avira.co...Thread&threadID=82163