Hi Ibrahim,
This is not a global issue of the model, that should be a problem with this particular router. The problem you decribe seems to be a router hang issue, the reason for this can various: hardware issue, lack of ressources, high cpu etc.
The best would be to open a service request with the TAC to understand the cause of the problem we'll need more informations, you can already try to collect these:
1- change the config-register to enable the break key
Router(config)#config-register 0x2002
2- reload the router to use the new config register (you can already try step
3 to 5 once to verify this is working fine before a hang)
3- Send the break sequence when the problem occurs. The ROM Monitor
prompt ">" or "rommon 1 >" must be displayed
4- Capture a stack trace. For this, collect the output from either the k
50 or stack 50 commands. Add 50 to the command to print a longer stack
trace.
5- Issue the c or cont command to continue.
6- Repeat the three last steps several times to ensure that multiple
points in a continuous loop have been captured.
7- After you have obtained several stack traces, reboot the router to
recover from the hung state
If you manage to collect some stack, open a new service request and add a "show tech" of the device.
If you could break in rommon at step 2 before the hang, but you couldn't during the hang, then you probably have a hardware issue and the router should be replaced.