Bug: "Use Item" function doesn't work (pvp=false; OSX)

This bug seems to be on the server side (Java version 1.7.0_25). Just ran in to the problem doing the following:
1. Closed minecraft server app
2. Added a user to ops.txt (no other ops in list)
3. Restarted minecraft server app
4. Banned user from minecraft client
5. "Right click" stopped working for some non-ops users (this issue follows the user independent of OSX version - tested 10.6.8 & 10.7.5)
6. Removing user from ops.txt & restarting minecraft server app caused user to lose "right click" on OSX 10.6.8 & 10.7.5
7. Adding user back to ops.txt restores "right click" function
8. Elevating affected users by "/op" restores "right click" function; "/deop" removes "right click"
Unaffected users may not have been online during "/ban" of user
Removing banned player (text file edit) does not fix the problem.

additional info:
when "/ban" player is used, all currently online players (OSX) lose the ability to modify server blocks.

additional info:

Non-op is unable to change blocks near spawn point if they were online when "/ban" was executed. This includes opening chests and using buttons.

Reopened.

This issue doesn't seem to be OS related. The affected users have the same problem when using a Windows 7 client.

Sorry. I figured it out. Adding an "op" turned on spawn protection. Not sure why it kicked in when "/ban" was used and also didn't affect all non-op players.