Dell Dimension E520 strange boot problems

I've currently got a Dell Dimension E520 with strange boot problems.
Sometimes it will startup totally fine and go into windows vista, but if I do a shut down and then startup again I sometimes get the Dell Bios screen then the screen goes black and all I hear is the hard drive working as normal but no windows loading screen or desktop. When this happens it takes between 5 to 10 restarts/power off's to actually boot into windows again.

I've taken out the bios battery and reinserted, a warning was given regarding battery had low voltage. (I am today going to get a replacement battery)

Would a low voltage battery cause boot screen issues eg just a black screen when the computer is turned on???

I've reset all functions via the bios and I know what i am doing on that side of things, but i can't explain the no screen/no video issues i am suddenly getting.

rolleyes