Cannot type quotation marks in MonoDevelop

When using MonoDevlop in Unity 4.3.2f1 (Windows 7, 64 bit) I cannot type quotation marks, tildes, accents or carets (', ", ~, `, ^). Searching on this issue shows many similar problems and were easily solved by changing the keyboard layout. I have tried changing the keyboard layout from Dutch - English US (International) to English - US but this did not resolve the problem for me.

No other software seems to be affected.

Edit: As a result I cannot quickstart the reference guide for Unity functions etc.

I have the exact same problem. I found a simple workaround by typing in the symbols in an external app (like MS Word) and then copy/paste the symbol into MonoDevelop.
But it’s a time-consuming work around.