And, as a last resort, you might have to make a service call. Reformatting the hard drive usually takes care of the problem but will destroy any data you had and make you set up your computer as if it was brand new. Bear in mind that a service call is likely to cost you around $100. If you bring your computer to a repair shop, they will likely charge you $50-100 as well plus it will be there a week or so.
If you do need to take it to a shop, try to find a well-reputed one. Some computer repair places are as bad as some automechanics, and may 'find' problems that don't actually exist or recommend replacing working hardware. This can be due to either plain dishonesty, or simple lack of knowledge/experience on their part.
If you have tried everything including killing the power and hitting F10 repeatedly during startup, and nothing is working, then this may be your only option. Be prepared to lose some or all the data on the hard drive. There is also the outside chance that parts of your hard drive are ruined. Some viruses do target the Zero Sector of the hard drive, in which case it is probably ruined. Aside this, there is a pretty good chance that they can get your computer up and running.
While there are some viruses, particularly older viruses, that targeted hard drives at a low level, these usually targeted DOS-based systems, and are now very rare (and most wouldn't run properly under Windows anyway due to the way the Windows HAL interacts with hardware). These days, almost all virus warnings that make mention of the "Zero Sector" of the hard drive are variants of a widespread hoax. Don't be quickly drawn in by such scaremongering, particularly if you already know the name of the virus in question.
In the future, I would look into a different antivirus program along with the one you are currently running. No program is perfect, and one will pick up something the other will miss. Look for one that protects against spyware as well--a virus can ruin your computer, while spyware can allow people access to account numbers and assist them in stealing your identity. For this reason, a good antispyware program is essential along with the antivirus.
Running more than one AntiVirus program concurrently can result in false positives and other compatability issues. Use a single reputable AntiVirus package, and most importantly, keep the definitions up to date. It isn't a bad idea to have a SpyWare program running if your AntiVirus software doesn't also specifically target SpyWare. Manually running such a program occasionally in addition to the automatic setup isn't a bad idea.