Just to add to Kevin's comment, this bill has become corrupted and thus why it keeps crashing.
We would first recommend that you complete a rebuild (File > Utilities > Rebuild Data).
If this does not fix your issue, you would need to delete the bill from the register and then enter it again. To do this, open your chart of accounts > double-click on the account that the bill relates to > find the bill in the register and click on it once > press Ctrl + D to delete it. Then re-enter the bill.