Try searching the forums here. (It's spelled RAM preview, not RAW preview - that might help you find some better results.) There have been several threads about it recently.
We need to know a lot more if we're going to help you.
Show a screenshot of your Timeline panel and Preview panel.
Please provide answers to the questions listed here: "FAQ: What information should I provide when asking a question on this forum?"
Lol ... i was ready to send a screen shot an try to reply those answer ... and the damn after effects is working again ... don't ask me why because i don't know.
but either way here are the answers and my replys:
1- What exact version of After Effects?
R: Downloaded After effects Creative Cloud and instaled the program from there so i guess i have After effects CC version 12.2.1
2- Have you installed the recent updates?
R: no i haven't i have instaled the program 2/3 weeks ago ... and do i need to have the Creative Cloud intaled to do them ?? my teacher said i needed to unistal it.
3- Operating system and Machine i use are on my profile
4- What versions of drivers for your graphics hardware do you have installed (including CUDA driver and driver for display adapter) ?
R: I have the 334.89 graphic controler from Nvidia, and PhysX - 9.13.1220, Virtual Audio 1.2.20 also from Nvidia
5- Do you have any third-party I/O hardware (e.g., AJA, Matrox, Blackmagic, MOTU)?
R: No i only have a cooler and a mouse
6- What kind(s) of source footage?
R: humm i don't know i use normal .mp3 musics from the net and .wav and use images .jpg and .png
7- If you are getting error message(s), what is the full text of the error message(s)?
R: "After Effects error: Raw Previem needs 2 or more frames to playback"
8- What were you doing when the problem occurred?
R: Nothing ... i simpli completed the project ... Cloud prewiew it once ... and then caput ... could not do more prewiews
9- Do you have QuickTime installed.
R: No i don't have ... my teacher said it was not necessary.
10- What other software are you running?
R: Right now ... i have Bridge, Audition, After Efects, Ilustrator, Photoshop, Flash, Indesing, Premier and Dreamweaver, instaled on my PC ... i also Have Blender a 3D Program, don't know if it is important though.
11- Do you have any third-party effects or codecs installed?
R: Do you consider Video Coplilot 3D element and Red Giant Trapcodes effects and MPC Codec pack in this category ... then yes i have.
These last questions i don't understand what you meant by them so i left them
Are you using OpenGL features in After Effects?
Does the problem only happen with your final output, RAM preview, or both?
Are you using Render Multiple Frames Simultaneously multiprocessing?
Are you using the ray-traced 3D renderer?
If the problem is with output, give your exact output settings (both render setting and output module settings). Screenshots help.
What is the exact sequence of steps that you are taking?
With Regards ASilva
PS: Tomorrow will see if it gives me the error again