We develop and sell components for other software developers through our website. The main products are ActiveX and WinFroms.NET grid controls. Some years ago we established a forum dedicated to our products, and it resides on the same website in a subdirectory (maindomain.com/forum). We left it opened for search engine robots trying to increase the occurrence of the specific keywords we optimized our website for - and thus have a better SEO effect (examples are "activex grid", "winforms grid control").
At some point we discovered that Google Webmaster Tools suggest us to fix some problems on our website, and the most of them are forum topic pages. For instance, we have a lot of "repeated titles" errors on our forum pages because of the forum engine we use.
So, the question is: should we hide our forum from search engine bots to avoid those errors (in their "eyes") and thus enhance our rank? And is it good at all to open forums like our one for indexing to have better SEO?
Some detailed info as an example. We use the YetAnotherForum ASP.NET forum engine. Google bot reports the "duplicate title tags" error for the following pages: