Facebook Issue (Sorry, an error has occurred) - Screenshot attached

Hello Friends,

I am facing a weird problem since couple of month. This issue is with Facebook only and happens with my home computer only.

Suddenly my Facebook starts giving SSL error or the following (Image) error

4928377843_bbc9f1d4cf.jpg

Normally this error stays for an hour or so but the point to be noted is that if I start my modem (from 192.168.1.1) the error disappears.
This issue is with Facebook only and occurres randomly and vanishes as soon as I restart Modem.
I am using PTCL Broadband (Wiresless Modem) but my computer is connected through wire.

Another thing to be noted is that as soon as I get this error on computer my Facebook on mobile (connected through Wifi) starts giving 403 error.

Any Help?

Thanks in Advance.