When I try to boot up my PC, I just get a series of beeps, the same as the two I normally get when the PC boots up normally, but continuously, and the monitor shows 'no signal'. The previous couple of times I was using the PC before this problem, the cursor just froze and then the system crashed. Any ideas?

Usually, startup beeps are an error code for what is wrong generated by the computer's BIOS's Power-On-Self-Test (POST) routine. These codes are often listed in the User Manual or other technical documentation available on the computer or motherboard manufacturer's web site. Lookup the beep code and start troubleshooting from there.

Could be video card

What model PC do you have?

BIOS Beep Codes

Computer Post / Beep codes (http://www.computerhope.com/beep.htm)

Bios Central (http://bioscentral.com/)