Can a 933 processor replace a 700 in a pent. 3 desktop?

It can, but it's risky to be replacing parts like that. Best to check with the manufacturer of your motherboard's website to see what CPU's (brand and speed) that the motherboard actually supports. It would appear that your system does not support the CPU, if it is not able to enter the BIOS setup screen. The performance gain of 933over 700 is barely noticeable on today's software - your machine is still going to be pretty slow.