There is a great myth that computers need to be shut down. Sure, every now and then is totally fine, but think of it from the other side. The Internet is up 24\7\365, every website on the planet resides on a computer (server) and those computers run 99.99% of any given day.
So, when a customer of mine says, "Well, I shut it down after every time I use it"...I mention the above to them and then tell them that the computer that I use for file storage has been "ON" since 2001 they are shocked.
Moral of the story: If it runs fine but has trouble starting up, DONT shut it off!!
ANYWAY, check the CMOS battery like mentioned above, make sure there are NO other CD's, flash drives, micro cards, etc plugged in and I say do the test....I love to gamble.