We have a customer in the USA who has two 1.5Mbps connections bonded into a Multilink connection.
On our monitoring we are seeing hundreds of thousands if not millions of receive errors per day (currently our monitoring - Solarwinds Orion - is reporting 215,000 receive errors just for today). This site is a DR site for the customer and they have advised they are not uploading / downloading any traffic to this site (our monitoring confirms this).
The two serial interfaces are error free, however the multilink interface is racking up input frame errors. We have had Verizon check both the lines and they came back clear.
Attachment with all the output.
Router is an 1841 with 12.4-16 IOS.
Edit: I found a similar thread here but no resolution: http://forums.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Network%20Infrastructure&topic=WAN%2C%20Routing%20and%20Switching&CommCmd=MB%3Fcmd%3Dpass_through%26location%3Doutline%40^1%40%40.2cd31c59