had the same problem! but mine happend with the snow! when i used my wipers and a lump of snow was sitting where the wiper usually rests it set it out of place, as already said quick unbolt etc etc does the job.
Yes I believe you do need a new/modify your existing crash bar For the conversion.
I'm sure It is mentioned in mattandrews conversion thread.
Well, Matt is the man in the know so I guess it does need to be done. Not sure where I read it was only for the S3 bumper it needed replacing/modifying but I've read it somewhere!
Anyhow, I'll be doing mine in the next 2 weeks or so (S-Line conversion), so I guess I'll find out for sure then... I'll be modifying my re-inforcement bar rather than replacing (if required!).