Vista - IP internet access problem

Hi - I need some help here.

I have just shifted into a hostel and the internet provider only uses IP internet access via IP phone.

I have been having unstable internet access (ie I usually am unable to log on to the internet at night but usually have no problems logging on in the day). Is there such a thing like "time activated virus"?

I talked to the internet provider helpdesk and we have tested that the lan line access has no problem (ie, my neighbours could access internet with their laptop using my lan cable, while I am unable to access the internet even if I use their lan cable). It also does not seem to have any problem with the capacity access (ie number of users who are logged on to the network).

The internet provider suspects that there is a problem with the settings. I have tried disabling the firewall and anti-virus system but it still does not help. I have ran the virus scan and there are no virus on the laptop either.

Appreciate any advice on potential areas to look out on settings etc as it is becoming like a "lottery" feeling everytime I log on to my lapop to see if I can access the inernet. Thanks!