Problem after ASA replacement

E Double U

We have an HA pair using 5510s version 8.4(5). The secondary unit is currently active because the primary has an issue. When we replaced the primary (we didn't failover yet) users reported issues with several services including webmail. The time people began reporting issues correlates to when our logs show the mgmt0/0 HW interface changed state to up.
We could see tcp connections building, but getting resets on the teardown. We powered down the new ASA, but the problem remained. During our troubleshooting everything just started working again without us making any changes. We thought it could be an ISP issue, but other services going out of the connection were working just fine. We are perplexed about what happened.
Any ideas as to what the root cause would be? Thanks in advance!

ram1101

did you clear the mac and arp table ?

E Double U

I don't think the admin cleared arp. If he did, he didn't mention it.

ram1101

that did it for me when one of my ASAs failed and i had to replace it, like u say some services would work but other wont, remember that that active ip is mapped to a mac-address

E Double U

Thanks Ram!

Did you only clear arp on that ASA or other Cisco devices as well? In our case there's another ASA, connected to a switch, etc.