strange delay boot time

Hi All

It's been a few days now that my XP hang on, while booting, for roughly
50 seconds on the blue screen where is written "WInDOWSXP". In the
meanwhile the HD has a blinking light. After that there is the desktop
launch and all seems to work correctly. The strange is that if I turn
off the adsl ethernet modem before booting no delay in desktop launch
is observed.
I have manually assigned the ip of the Ethernet card. A virus & spyware
scan has been unsuccessful. Event viewer found no error.

Thanks in advance

Regards

.