Have had this happen due to a few different reasons over the years. Your best bet is to reference your logs to determine what action is best. If you are not familiar with the logs, or do not have the time to search; I would suggest you open a case. So with that, confirm some details before you try anything
- Corrupt Folder/File/App - repair - InfoService, JobEngines
- Under Resourced Systems - check/trend hardware resource use, db IO
- only way to fix this is to add resources, or decrease your DB size
- this can also manifest in a few different ways, and if the case you will see constant issues, delays, slow load, etc. (If you do not see your cpu, ram or NIC constantly peaking at times then look for something more simple than this possible rabbit hole)
I have also seen Full Transaction Logs manifest this issue in a few client environments.