c3845 with 256MB RAM hangs when trying to receive full internet routes

We have a cisco 3845 Router with 256MB RAM. It connects to our ISP on an E1.
The IOS on is c3845-entservicesk9-mz.124-5a.bin
The Utilisation ont eh E1 is less than 25% during the night times when we attempt the below:-

The problem is when we do a BGP peering with our Service Provider's core router, teh ROuter Hangs in less then 5 Secs.

When I say its hangs , it actually stops processing any IP INPUT.
The LEDS & Console are available at all times during the Hung state.
But I cant ping my own interfaces, All my BGP peers go down from ESTABLISHED to ACTIVE.
I lose all routes, including the ones i have from my IGP.

Reload is the only way to get the router UP again.

Is the hardware strong enough ?
If it is, Is this a software Bug ?

Any help from you folks will be greatly appreciated.