Honestly, I can't see a monitor being non-compatible with XP. Video card, yes, but not the monitor. But that's just me.
Karen, thanks for the suggestion. I will ask my computer-guy to check it out when I take it back to the shop on Saturday. It might at least explain the reboot thing, though not the modem problem.
Further tests showed me that it's really a problem of order in which I do things: if I connect to Wanadoo before opening OE, it freezes. If I open OE first and connect to Wanadoo from there, it works.
Kaethel
(your computer-challenged FoLC)