X3XE question

I have been working with the response line and they are really no help. We are having a problem on our World side in AP. If we change a voucher (P04105) with foreign currency, we get an error message: decimal data error. The reponse line person is giving me all these things but nothing seems to do with AP. They have told me that I have to apply the PTF X3XE. What is this PTF? We have applied the X3 PTF over a year ago, so why this new PTF now? We are on A73 cum 9

Thanks in advance for your help.
Stephanie