Topic: Pianoteq 'forgetting' IR files

In Pianoteq 6 standalone, I have several presets which use external impulse response (IR) files for reverb. The IR files that I use are always stored in the same folder on the computer. Quite often, when I return to some presets after a while, Pianoteq 'forgets' the name and location of the IR file ('file not found!' in the reverb section), even though I haven't moved or renamed the source folder - so I have to recall which IR I used (fortunately I usually include a clue in the preset name), and reload it. Has anyone else encountered this problem? Is there a solution?