In ITIL backed organizations the term Problem is used for recurring errors which need a long term solution, while Incident is an error that have a relatively quick solution. As most issues reported to a helpdesk is of the Incident kind, we decided to use that term instead.
As the PF HelpDesk V11 ticket form is easy to customize, you may of course use any terms that suits your organization in the tickets. However, from version 11 Incident is the default term for the problems, suggestions and other issues that PF HelpDesk helps workgroups to cooperate on.