Freaky keyboard after Sheur trojan then Vista reinstall

Hi

My keyboard had gone mad! Firstly the number keys stopped working, now many of the letter keys won't work or the machine thinks that the ctrl key or function key is pressed when it isn't. It has got so bad that I can't log on.

My Dell Inspiron 6400 running Vista 32-bit was recently badly infected with Sheur trojan and other viruses which wreaked havoc with my machine. I went through the lengthy extraction process following the READ ME FIRST instructions to the letter but problems still remained, particularly with the keyboard. I was so desperate, I reinstalled Vista and formatted my hard drive. The keyboard issue is as bad as ever and the machine now keeps beeping randomly and continuously at me (much like it did when it was infected but it can't be infected now - surely?).

I desperately need my machine working! Please help!