Hi Laurent,
Thanks a million for your answer, it seems we are 100% hitting this bug as we are doing a shut/no shut on the interface and loosing the access during approximately 2 minutes.
The only issue being the cisco bug details indicating the bug is fixed in 12.2(33)SXH3 (we are in SXH3a)......Maybe you have a different information in your internal databases stating the bug is resolved in SXH4 for the 6500..
Thanks again.
Karim