I'm experiencing the same issue with delay objects being greyed out. When I look up help on the object, the help patch opens fine but even there the delay object is greyed out. As suggested I've checked linked file preference locations for existence of anything named "delay" but there's nothing (other than delay.mxe in the max folder). I also scrapped the entire Max 6 Preferences folder but the issue still remains. Any other suggestions? Cheers!
Made a copy of delay.mxe in the max-externals folder and renamed it "delay_.mxe". Started Max and tried to instantiate "delay_.mxe". It didn't find it. Then, I changed the object to "delay" and all of a sudden it picked it up. Go figure!!