Cisco 1601 router fail

[admin_2]

I have Cisco 1601 routers at my branch offices and cisco 2611 and 2610 at the head office. Each branch office is connected to the head office via 64k point to point data line. My problem is that, at my branch office, routers always fail mostly 4 at a time. The medicine is that i tell poeple at the branch offices just to reboot the routers. I always notice this when I telnet my head office router and check the serial interfaces using the show interface command and on the failed router the interface which they use to connect to the head office are reported as line protocol down. What could be causing this problem?What are the possible solutions?

[steve.barlow]

So the 4 failures are because the 2600 interface went down. How many serial interfaces do the 2600s have? Is it always the same router, same interface?

Without more info it's have to say why, but here is a good link to start with:

http://www.cisco.com/univercd/cc/td/doc/cisintwk/itg_v1/tr1915.htm

If this doesn't help, we may have to look at bugs or something else.

Start with the link and let us know.

Thanks

Steve