Windows 7: Must push F1 to Boot Win 7

I've just installed a new video card (Sapphire Radeon HD5570) in my HTPC and now it won't continue to boot into Windows without a trip to the BIOS (for nothing but exit) or just a push of the F1 key. Each time I boot now I just push the F1 key and it boots fine and the machine works normally forever. What's happened?
I should mention that I originally tried to use a new MSI card and gave up on it because it also requred the F1 key push. So that's two separate new video cards that will not boot normally.
Motherboard is ASUS P5N73-AM with 2gb of RAM, WD740 Hard Drive, running Windows 7 Home Premium 32bit.
Thanks for your help and advice.

You may need to disable a warning setting in the bios.

How To Disable "press F1 To Continue" When Booting Make Change Bios Boot

If that doesnt work, look for F1 prompt settings elsewhere in the bios. Also, try disabling the floppy/diskette drive in the bios.

Thanks Bill2 for your reply. I again sifted through the BIOS for the possibilities you mentione but could not find anything like the BIOS settings in the example. I've gone through and through and tried different settings but nothing seems to work yet. I have a suspicion that the F1 problem may be connected to the fact that I have two drives in the machine, one is an old ATA and the other is a small super fast SATA drive. The boot order setting is only for "hard drive, cdrom, removable drive" and nothing else. In another BIOS screen in "Boot settings" the two drives are listed as #1 and #2. The ATA drive has been listed all along as #1 so I changed it to have the SATA drive as #1 but it made no difference. I don't know where to go from here.