"Save to Web & Devices" grayed out

I'm using Adobe Photoshop CS5 and have an odd problem. For some reason, my option to "Save for Web & Devices" is always grayed out. Regardless of the file type I'm working on (tif, jpg, png, etc.) or color mode (RGB, CMYK, Grayscale, etc.), I can't save my images for the Web. I've made sure the image was 72 ppi too, although that really shouldn't matter. I've checked my preferences, but there doesn't seem to be anything to check/uncheck that relates to this issue. Any ideas? Thanks.

Problem solved! Somehow my Save for Web plug-in (located in my Import-Export plugins folder) got deleted. A friend of mine emailed me a copy of his Save for Web plugin file. I dropped it in my Import-Export folder, started up Photoshop, and Voila! I'm now back to normal. YAY!!!