Pretty easy, in fact.
Assuming you have a field in that entry with the e-mail address of the record's creator (or in a linked Users table), you can set a script trigger on the problem description field (in edit mode, right click the field, set script trigger) for OnObjectExit to trigger a script.
Then you just need to make a script with the "Send Mail" command that populates the "To" field with the e-mail address of the creator, and the "Message" field with the contents of the problem description field.
There are various settings you can play with, including: using a button to trigger the script instead of a trigger (so it only sends when the user is finished), sending via the user's mail client or configure an SMTP account directly into the script step, options to copy the user, etc.
RG's advice is good. I'd probably use an OnObjectSave trigger instead of OnObjectExit, though. If a person clicked into that field accidentally, did nothing, and then clicked somewhere else, the script trigger would fire and send an email. Using OnObjectSave instead would send the email only when some change had been made to the field.
Great. Thank you RG and dtcgnet!