Hyjacker?

[YoMoma]

Got some malware on my pc. Tells me any program that I try to start up is infected and wont open them. It does give you the choice to run anti virus, in which it shows a fake AV program (not mine) running a scan.
The only website i can view is the one page where I can purchase Their antivirus.
I had something VERY similar a year ago on another pc. This pc is running Windows Home edition.
I was able to start this pc up in safe mode and run my Malwarebytes program to get rid of the hyjacker. I pressed F8 during startup to get my XP pc into safe mode. But my current pc with this problem is running Vista Home premium 64bit and hitting the F8 key only gives the option on what drive I want my pc to boot up in.
I`m hoping the same method will fix my pc but I cant get it into safe mode.
How is that done with Vista?

[Piglet1]

You say that the F8 function is not working but this is the usual method
for booting Windows Vista in safe mode.
Are you hitting the F8 key repeatedly imeediately after the first blank screen appears or after the BIOS post ends? If not try it. If you have already been doing this and it is not working, try quickly hitting the F-Lock (if your computer has one) key before hitting the F8 key repeatedly.
If this still doesnt work there are a couple of things you can still try
a) Press the WinKey and R to open the run dialog box.
Type msconfig and press enter
Click the boot tab
Select the safeboot check box (tick)
If it is not already- select minimal
Click apply
Click OK
Reboot the computer
*When the computer restarts the advanced options menu should appear
** Remember to undo the changes when in safe mode to return to your preferred boot mode afterwards!!!
b) You can try what I refer to as a hot shutdown. Whether this is the correct term or not I don't know but it goes like this:
Hold the power (on/off) button down on your machine when it is already
up and running. This will shut the machine down after a few seconds without
choosing the actual shut down option. When you restart the computer you
should get the option to boot in safe mode as Windows will detect the shut
down procedure you have just used as abnormal. Easy!
Good luck with the rest of your problem
Cheers