I am having a consistent issued with Antisocial when trying to edit a contact in Yahoo! mail.
Using Firefox 5 or 6 beta on win 7 x64
Filters in use: EasyList + Malware Domain + Antisocial
After testing I have found that only these two rules are causing the issue:
/linkedin.$domain=~linkedin.com
/twitter.$~stylesheet,domain=~twitter.com|~wwe.com
When EITHER rule is enabled, then the problem occurs. Only if BOTH rules are disabled is the problem fixed. It is also not a combination issue with EasyList and/or Malware Domain. For testing only Antisocial filter was active.
Unfortunately that is where my debugging skills come to an abrupt end. I can see in the frame source that complete info for all contacts are loaded when the contacts tab is clicked. So the issue is seems to be buried in a css or javascript onClick or similar event that simply displays the info on the right side.
Steps to recreate problem:
1) temporarily disable Antisocial filter in Adblock plus
2) create or use an existing Yahoo! mail account.
3) if no contacts exist, create a contact with name and email. save.
Click on Contacts tab.
In the middle column, click on the first contact (not the email address link).
Correct behavior is for the contact's information to show in the right half of the window along with Edit and Delete buttons.
4) sign out of yahoo. clear browser cache and restart browser
Note: I found step 4 was not really required, but included it to make sure. I used a page reload in subsequent tests.
5) enable Antisocial (all rules)
6) sign into Yahoo! mail.
7) Click on Contacts tab.
Follow 3) above. My observed behavior is that nothing happens when a contact is clicked. There is no contact information, nor Edit or Delete buttons.

9) reload the yahoo page. Follow 3) above. My contacts now behave properly.
Hope this helps.
Keep up the great work!
-- MartyG