my 2500's or 2600's will lose their SAP and Server tables for no apparent reason. they are running 11.3, are there any know bugs that will cause this, I cannot find any.

I have serval 26oo seris routers that will drop the IPX routes and servers at wiil. They are running 11.3, has anyone seen this problem and is there a fix outside of upgrading the IOS

I have a number of 2610's running 11.3, they will drop IPX routing and servers with no reason. The only work around I have found is to reload IPX routing. Has any body else seen this problem and is there a fix.