I noticed lately when I install Oracle 10g on Windows or Linux, when I try to install/configure Enterprise Manager Database Control (DBConsole), it errors out and will not complete. No matter what I tried, dropping & creating the repository over and over, still didn't work.
I stumbled across Oracle Metalink Patch 8350262, which supposedly fixes the issue. The issue is that the self-generated certificate expired on 12-31-2010. After installing 10g, apply Patch 8350262 (it is an opatch patch), everything went fine as usual. I hope this saves you some headache and time.