On a pix you can give clear access-list counters
this is available only on the following version ( 6.0(4), 6.2(1), 6.2(0.101), 6.1(4), 5.3(2.201), 6.1(1.100), 6.0(1.106) ). Actually the command was introduced as a result of the bug with bug ID CSCdr84768
Refer link for more information
http://www.cisco.com/en/US/partner/products/sw/secursw/ps2120/prod_release_note09186a00800f1efa.html
Hope this helps
