Question : why would I get a clock change on my ATM interfaces

why would I get a clock change on my ATM interfaces? I see them in my syslog server just before the line protocol on the interface goes down. and then I lose all connectivity until the clock change is removed. Sometimes it goes down for hours..

2006-07-17 11:51:28 Local7.Notice 64.222.x.x 42: Jul 17 11:51:28: %SYS-5-RELOAD: Reload requested by admin on vty1 (64.222.139.2).
2006-07-17 11:53:17 Local7.Debug 64.222.x.x 18: *Feb 28 19:00:20:  clock change done for int ATM1/0
2006-07-17 11:53:18 Local7.Error 64.222.x.x 20: *Feb 28 19:00:21: %LINK-3-UPDOWN: Interface ATM1/0, changed state to down
2006-07-17 11:53:18 Local7.Notice 64.222.x.x 21: *Feb 28 19:00:22: %LINEPROTO-5-UPDOWN: Line protocol on Interface ATM1/0, changed state to down
2006-07-17 11:54:10 Local7.Debug 64.222.x.x 22: *Feb 28 19:01:13:  clock change removed for int ATM1/0
2006-07-17 11:54:12 Local7.Error 64.222.x.x 24: *Feb 28 19:01:15: %LINK-3-UPDOWN: Interface ATM1/0, changed state to up
2006-07-17 11:54:12 Local7.Notice 64.222.x.x 25: *Feb 28 19:01:16: %LINEPROTO-5-UPDOWN: Line protocol on Interface ATM1/0, changed state to up

 I have been fighting this problem for three days and can not figure it out.

Thank You.

Answer : why would I get a clock change on my ATM interfaces

The clocking has to match on both ends- in the case of ATM, the ends are your router and their ATM switch. So there's not much you can do except hound them until they fix it.