Well, I have Windows XP SP3. I uninstalled the final version and I tried all the betas. Everything works until the beta 8. The problem appears from the beta 9. Perhaps as Peter says, the fact that "PTE remembers whether the user had the waveform showing or not the last time they used the Timeline view" is involved, specifically with some hardware? Another guy has Vista and has no problem until the beta 11 included. The problem appears at the opening of PTE, and at the loading of the first project ("Load Last Used Project" option is on or off). After opening a second project in the same session, everything works until closing pte. Another way to avoid the problem is to open PTE in "slides" configuration (the previous session must be closed in this position). After changing to "Timeline" the button works fine. Igor, thank you for the work and sorry for this very marginal problem. Regards Eric