try what Joemama recommended.
But....
if THAT doesn't work, then it could be that there's a missing file or reg. entry, possibly removed by accident or a program (registry cleaner maybe).
now, you can always do a system restore, to restore those files and reg. entries.
OR if you're system restore doesn't work or is turned off, you can re-install windows COMPLETELY, and that MAY help. but only do that as a last resort!!
Finally, it could be that your ip adress is malfunctioning.
if your desk top computer (if you have one) is expierencing the same problem, it is more likely that this is so. You can always contact you ISP and ask them to give you a new ip adress.