Milo, it only started happening just before the CMOS battery went tits up, after changing the battery everything now works as it always has done, the computer still arrives at the log-on window before the router finishes initialising, but I no longer have the problem, after all it's been running this way for many years without any problems, since it only faltered when the CMOS battery was on it's way out, it seemed to me that it must be causing a hardware glitch on the motherboard in so much that something wasn't being initialised properly by the bios, and I was hoping someone could tell me which bit. Sorry perhaps my question was a bit too esoteric for here, it's just as an ex service engineer I don't like things doing something out of the ordinary and not find an explanation for it.
Incidentally the router only takes about 25sec longer to fire up than the PC which is about 2minutes,