This seems to be a Regression introduced in 3.0:
Start the SnippetParsers sample and switch to VB.NET. Now start a new line and type "if ". Then wait a second so that the code completion popup appears. Now type an opening bracked "(".
The editor inserts the "False" which seems to be the selected item in the popup, then enters the bracket. The result is "if false(".
This is a bit annoying ;-)
Fixed by AlterNET support. Many thanks!