First of all, welcome to BC !
Next, try starting your computer in 'Safe mode'. You most commonly do this by pressing the 'F8' key while the BIOS screen (the one with the manufacturer's logo all over it) is showing. If 'F8' doesn't work on your computer, look at the BIOS screen for what key gets you to the boot menu. This will bring you to a black screen with white text. At the top there are three variants on 'Safe mode'. Use the up and down arrow keys to select the 'with networking' option and press 'Enter'. This will boot the computer into safe mode. Don't worry about the appearance - it's a black screen with an even array of icons and 'Safe mode' in each corner. Let it finish booting, then shut it down again. This simple procedure cures a surprising number of errors !
If this doesn't solve it for you all by itself, there is quite a good discussion of how to solve the problem here :-
Essentially, if 'Safe mode' didn't solve it, then you need to do a Windows repair of some sort. Re-boot and press 'F8' ( or whatever key it is on your computer ) again but this time arrow key your way towards the bottom of the 'Safe mode' screen and you will see two choices, roughly, 'Repair Windows' and 'Last known good configuration'. Choose 'Last known good configuration' and again press 'Enter'. Your computer will mutter to itself for a minute or two and then usually - not always - burst into life. If it does, great - problem solved.
If it doesn't work, then repeat the process, but this time choose the 'Repair Windows' option, and press 'Enter'. Again, this will usually work, but may not.
If it doesn't, post back with a note of what you have tried and we will take it from there, but have a look at the article referenced above.