It appears that the saga is over at last. After two new NICs, development of a new range of creative language and much helpful advice from Press F1, I have now gone a week without a lockout so I am probably safe to say the cause is known.

As I mentioned in a previous cautious post before I got my hopes up, quite by accident I stumbled over two entries in my startup menu for programs that I thought shouldn't be running. These were TweakUI and TweakDUN, neither of which appeared in Task Manager either. I routinely unticked them and after rebooting, it slowly dawned on me that my problem was gone!

I have since checked and although TweakUI is still installed, TweakDUN had been uninstalled long ago because it made the computer unstable and kept popping up at boot.

I decided not to tempt fate by ticking either again to see if the problem would return, so I'll never know for sure which one it was.

Many thanks to all at Press F1 who continued to respond to my posts, you gave me the confidence to keep looking for a solution.

OS is Win98 original +SP1, P166, D-Link NIC, Connection Jetstream/Xtra via Nokia Router and Email Client Outlook 2000, for anyone who might want to speculate on reasons.

Happy (boot-free) days,