How old is the PC?
Did you put it togeter or was it bought from new?
BIOS ROM CHECKSUM ERROR usually means flat CMOS battery and lost hard drive drive settings hence the search from floppy
Floppy light light on constant is usally floppy cable wrong way round. henve the above questions.
Battery first, £2. 99 pack of two C2032 from wilkinsons stores.