The root CA (A Windows 2003 SE server) in my domain crashed and had to be restored from backup. During the process the cert service had to be removed and re-installed. Although the cert server seems to be working now (I can access the web enroll site, and "user certs" can be successfully requested), I cannot successfully request a computer certificate on any WinXP client using the certificates mmc - every time I try I get this message from the Certificate Request Wizard: "The certificate request failed. The parameter is incorrect". As I mentioned before though, this seems odd because when I request USER certificates using the certificate mmc, I have no problem. I thought it might be a problem with the computer account on this particular client machine, so I deleted if from the domain and rejoined, but the problem persists.