Flashing red in time display?

Hey everybody, Been using Reaper for a little while now, but in some of my projects, the time display flashes red, not all projects do this. Is this due to CPU usage? Too many VST's? It doesn't seem to be a problem (yet, hopefully), but can anyone tell me why the time display flashes red? I tried using the search function, but couldn't find anything. Thanks in advance.

I think that it flashes red if audio dropout occurs. Increase your buffer size.

... it's a temporary audio hiccough, could be caused by CPU load at that instant. Is anything special / exceptional happening at those points in your projects?

Thanks everybody, It does it just kinda randomly, but mostly when I have T-Racks & EZ Drummer running at the same time. I guess I just need to render to stems & that would solve the problem. I use ASIO4All, & if I remember correctly, I have the slider as high as it will go. Now for tracking, I use a Tascam US122L, & if I have lots of tracks & FX, I have to disable a lot of them, or I get terrible dropouts. I have learned to cut back on my FX use, but yesterday it flashed red with only a few tracks running. My Tascam has been notorious since I've had it, but I'll have to make due for a while, money's pretty tight, but I think I can manage for a while! Hopefully a new PC will solve a lot of my problems, currently using a Dell Inspiron 1526 laptop, with Vista. When I finally do get the new PC, it'll be a desktop, & I'll have XP as my OS. Thanks for your help & quick replies, I love this forum, learned so much in just a short time here. Thanks again!!!!

T-RackS can use a lot of CPU at time, depending on what is loaded. Display the Performance Meter (Ctrl+Alt+P) and watch the CPU load on each track during playback.

Yeah I know, I use the performance meter a lot to see which VST eats up my CPU, & T-Racks is pretty hungry sometimes. Thanks Dark Star, I guess I'll just have to alter my workflow until I get the new PC! I just wasn't for sure what the flashing red meant. So, now I know!! Thanks again!!!