AVI is an audio/video file format that stands for Audio Video Interleaved, which is the Microsoft Video for Windows standard. Because it is a standard and popular (though very big) format, it can be opened in and played by any multimedia software able to play video and any video editing software. RIFF stands for Resource Interchange File Format. It's not a format but the structure that defines the format (AVI). If there is error or corruption in the structure, the AVI file is not recognized. Provided you have Microsoft Media Player, Quicktime, or Real Player installed on your computer, you should be able to just double click on that AVI file and your default player will run it. If nothing happens, there are likely some errors in the structure. I only suggest doing that to make sure the program you are trying to open it with is not in error of not recognizing that file. I have had that happen before. If there is corruption, it could have happened during download and you simply need to download it again. If you are able to play it in one of the Windows multimedia players, you may need to try a different program. BTW, Windows has a free video editing program calld Windows Movie Maker (it's probably already on your computer) and there are other free ones you can download from the internet. I'm afraid I am not familiar with VirtualDub. Once you are working with a program to play all your files, they can be dragged and dropped onto the timeline one after the other, then viewed and saved as one file whatever the saving/rendering process is for that program. I mostly use Studio these days, which offers a "Make Movie" button. You just have to become familiar with the machinations of your application. As I mentioned before, AVI is a very large format. Once you edit to make them all one movie, you have to be sure there is enough hard drive space and memory. A two-hour AVI file can be anywhere between 40 and 60 gigabytes. I don't know what operating system you're running but can tell you Windows 98 cannot handle it no matter how much hard drive space or how much memory you have, especially since it cannot handle more than 500m of memory. The fact is, Windows 98 is simply unable to supply the needed resources. When I upgraded to Windows XP, it was exactly for that reason. Even with XP you need at least a gig of memory to prevent dropping frames. Additionally, it will take many hours for it to render (another word for save that involves intensive formatting). This is especially so if you want to get fancy and include the special effects and transitions that are available in the program. I let mine render overnight and sometimes it still is not done when I rise the next morning. I suggest you save it as an MPEG instead of AVI. It will not be as huge a file and will not take as long to render, but a two-hour file will still take a long time. MPEG/MPEG2 are also a popular and standard file formats. Clear as mud? Did I help...

Try ad-aware. If it can't clean the virus because it's running, it will clean it on the next startup.

DA, I did go to Filehippo and download the QuickTime Alternative. I also checked out Ravencajun's suggests, but the Quicktime site was rather confussing for me. Anyway, the QT Alt. worked perfect!! After I downladed it I scanned the file and then installed it. When I went to the folder where the mov file was and clicked on it, thinking it would ask me what I wanted to open it with, but it didn't even ask....It just opened up in the QT Alt. and played. Again I Thank both of you ((hug))

Maybe I don't have a PDF reader. I looked in Control Panel> Programs and it shows a PDF Complete, but I can't find it in "All Programs." What PDF reader do you all recommend? I normally shut down my computer totally for one overnight per week. Starting it again has not helped the issue. I haven't even seen the popup for Protected Mode come up when I tried downloading the PDF documents.