Does anyone else have this problem?

When looking at my sms conversations, I can't scroll up to look at older texts. This seems to happen if a text comes through whilst I am on the sms screen. It only lets me scroll to the last couple of sms messages, ive tried deleting some messages thinking maybe theres to many on there but that has no effect. Also pressing R to reply does not work.

Any ideas how I can fix this problem?