Sparrow mail app seems to make my imac act funny
When first launched, Sparrow can be pretty intense on your harddrive and internet connection, since it's downloading every email.

About the column thing, it was probably still syncing your labels and everything, and that's probably why it was misbehaving.

About your WiFi issue, it could be the same thing, since Sparrow is downloading every email, you WiFi router or connection is probably too weak to handle the load and crash.



My advice would be to delete your account from the app, connect to a wired connection, re-add your account and wait 20-30 minutes (depending on the number of email you have and the size of your inbox).