I would recomend a reinstall or install of the SSDT for VS 2010 at this point. Also is this the server or your development system that this is occuring on?
Either way try to update or install MDAC on each one.
Once everything is confirmed patched and running at the latest releases and it still does not work look into this.
The SQL Server Agent Service account, account used by SSIS runtime, and your logon each use a different Temp directory when you are logged into and executing SSIS directly on the server. The actual directory used is located under C:\Documents and Settings\AccountName\Local Settings\Temp. Once the SSIS package execution Proxy account is granted read and write access to this directory the package should start acting better.
If you still have the issue there is a bug specific to SQL 2008 that is listed here. If you have not installed this fix try it.http://support.microsoft.com/kb/933835
Technet.microsoft.com and msdn.microsoft.com are full of good information on this error if you search. Be sure to try limiting your search to just items in the Library and knowledge base before trying the items posted to the social links.