Now this issue is a bit different. One of my moderators cannot reply to a conversation but he can if he starts his own and invites others. That is weird. I checked the account permissions and they were normal (just like the other moderators). He has a very powerful computer/ latest os (Win 7 pro, AMD Phenom II 964 Black quad core. 4 gigs ddr3. Gigabyte ultra durable 3 mobo. It's a high power gaming computer. 600watt supply. GTX260 vid card.) and latest browsers (ie 8 and firefox) and he's also tried dumping browser cache but none of that worked. He also allowed me into his account and I could reply to pcs like normal so I can confirm its a problem at the userend. Now does any have any idea what could this be.
I have the same issue now, I (administrator) can't respond to conversation from a member but can start a new conversation.
Using XenForo 1.1.3, Blush skin from Xenique, XenTag & a few anti-spam addons that I've been using on several forums since ~September, FireFox 19.0.2; no high-end gaming PC here, just an el-cheapo $400 laptop from Costco.
Same issue using Opera 11.64; ditto for Default Style using FireFox.