My bet is someone was in the Services.msc and shutdown "something". I do not know your system and your modifications from stock.
Review http://groups-beta.google.com/group/microsoft.public.windowsxp.general/browse_frm/thread/522ade8479f4246d/6e12cdbb077fb455?q=%22Diskeeper+could+not+initialize+as+a+listener&_done=%2Fgroups%3Fq%3D%22Diskeeper+could+not+initialize+as+a+listener%26hl%3Den%26lr%3D%26sa%3DN%26tab%3Dwg%26&_doneTitle=Back+to+Search&&d#6e12cdbb077fb455
Bob
I bought a copy of Diskeeper 9.0 Pro and installed in on a Win2000 machine. When I tried to bring it up, I got this error message: "Diskeeper could not initialize as a listener. Please see Event Log for more details." The short printed user guide had no reference to event log, but the detailed user guide on the CD offered some help. It said to go to My Computer, select Manage, then System Tools, then Event Viewer, then Application, then Action, then Properties. In properties, set Max Log Size to 2048 KB and enable Overwrite Events as Needed, then select OK. I did this but still got the same error message. I went through the rest of the detailed user guide and found nothing that seems to address this problem. Thanks for any help.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic