comment settings are set to closed, unable to change it + undefined index and invalid argument warning

Hi, I installed the beta1 version and everything worked fine. Recently I made an update to beta2 and now I noticed that all my comment tabs (on all nodes) were gone. On every node edit page the comment setting was set to "closed", when set to "open" again the changes didn't applie. So I went back to beta1 version but that didn't fix it (in the meantime I upgraded from core 7.8 to 7.9). The tabs are there but it's still the same problem, the comment setting is set to "closed" and I cannot change/save it. When viewing the comments (click on talk tab) no comments are shown. Instead the message: There are currently no comments on this page. But I know there are comments on the page! When viewing the node I get these errors:

Notice: Undefined index: comment in talk_node_view() (line 156 of ...sites/all/modules/talk/talk.module).
Warning: Invalid argument supplied for foreach() in talk_node_view() (line 163 of ...sites/all/modules/talk/talk.module)

I tried the dev version as well but it's the same like with beta2, no talk tab is shown.
On beta2 and dev I don't get the above errors.

Any help would be very much apprecciated!