Why Does My Computer Fail to Connect to the Internet at the Start of Each Month?

[crazy student]

My computer is connected to the Net through wireless LAN network.
It(my computer) fails to connect to the Net at the beginning of each month,
after I restored my computer a few days backwards, the problem was solved.
But this time I can't solve by restoring, my computer can continually connect to the Net though, but most of the time it fails. NB other computers in the network can function well, and the transmit signal to my computer is fairly good.
What's the problem with my computer?
It must not be the problem of hardware, otherwise it couldn't be solved by restoring.
Virus scanning also shows that there is no virus on my harddisk...
I wonder if it is the setting of my comp. changes every beginning of the month, if it is so, how can I stop it?

 

[Wrichik Basu]

Is it a problem of your computer or your ISP? Assuming that you have a monthly paid connection, there are chances that your ISP has some setting on their server that hampers your connection. I deduce this from the fact that the problem comes at the beginning of every month. Viruses will generally not work with such a good periodicity - they tend to be random.