Router Interface Resets

Hello,
I have a problem with router 1811. I have many Interface Resets on my WAN interface (Fa0).
The interface does not change the state (I checked the debug int fa0 and there is no change of status, and also I have a VPN connection established on the interface and it never drops) but the interface resets increase non-stop.

Is there anything that I can check for this issue?

Thanks for your help,
Mehdi