Dell :: Inspiron 1150 Looping The Loop

My Inspiron 1150 was in normal use last week. Next day I switched it on and it came up with the start screen, Dell, Inspiron 1150, the bar at the bottom screen fills with white as usual and in the top right of the screen it shows F2 setup and F12 boot menu.

Entering either of these does nothing and the whole thing goes round in an endless loop hence the title of the thread.

I have checked as far as I dare inside, checking the memory firmly inserted, battery is fine and the HDD looks OK though I don't have the gadget to check it like the old ones with 2 lines of pins.

Someone said it might be the CMOS battery but since the on-line manual doesn't show where it is, I can't replace it (even if that is the possible cause).