Check your machines first

Without detailed info, I could only think of:

First, make sure that your laptop is ok without being infected by spyware, worm, or virus. Make sure that it works normally offline. Second, check your desk top if it is clean of those infection. Third, connect your laptop to router through ethernet or USB port, or to modem directly and see if it works too. If you did not do any configuration change after your purchase, your router setting should be factory default and it should work without any change. Weak signal level could slow down your laptop online speed but should not freeze the machine. Anyway, check your machine offline first.