Nobody can tell you anything without exact system info or other technical details. Aside from that I see nothing unusual. RAM previews are called that for a reason and always have a limited duration thatr is determined by the available system RAM. You may simply not have enough of it.
AS Mylenium says, RAM Preview duration is governed by how much available RAM is in your computer.
To increase the duration of RAM Previews, reduce the preview resolution. You can also reduce the preview frame rate from the Preview panel.
If you still don't get enough preview time you might need to consider adding more RAM to your computer.
Thanks for the answers
You are right, here are the specification of my PC:
Windows 7 64bit
AE is installed on a SSD drive
Nvidia Geforce GT 425M
I just would like to do a ram preview of approximately 10s, that does not seem much, reducing the preview resolution does not seem to make it faster... It simply
I was wondering if by any chance, I was doing something wrong and AE was processing more stuff than it should ?
When you say it gets stuck, could you be a bit more descriptive?
Also, what, exact, version number of AE are you using?
Sorry for this issue. Did you ever find a solution? Please let us know if you have or if you still need help.