I think you are experiencing this bug?

There is no fix that i know of, and since the virtual keyboard is closed source, I guess "we" can't fix it - only "Nokia" can (hint: don't get your hopes up about that)

You can always try to install a third-party virtual keyboard like FastSMSEvo (never tried it myself though, is that one bug-free?), but that's just a workaround off course because it replaces the original keyboard entirely by a different keyboard, instead of fixing your problem.