How can I get around this for now? (Tempo change makes clips disappear) [SOLVED uh..sorta]

I just posted this in the Problem Reports forum, but I'm also looking for some workflow ideas on how to work around this for now.
 
I have a project which has hundreds of linked clips and edits. I've found that when a Sonar project gets "bloated" like this, clips start behaving badly. They move around by themselves, disappear or change clip start/stop times. Here's a video of what I'm talking about; when I try to insert a tempo change, it ends up rearranging all the clips in my project.
 
youtube.com/watch?v=1HxdPYOJt30
 
Any ideas on how I can avoid this? Is there some secret way of locking clips so that they don't move? I know I can bounce them to single clips in their tracks, but since I'm not done editing I'm not ready to finalize them like that. I'm on Sonar 8.5.3, Windows XP64. Thanks.

Hi Anderton, your suggestions didn't solve my problem completely but it got me closer to a fix. Locking the clips (both position & data) didn't alter anything, nor did Apply Trimming. But I did notice that all the tracks that got messed up contained clips with V-Vocal.
 
I'm not ready to render my V-Vocal clips yet, but I bet that would solve things.
 
Another interesting thing I noticed, when I was trying your suggestion of changing the tempo in Tempo View, I saw that it didn't make a difference when changing the tempo at that particular spot (measure 65), but when I changed the tempo further down the timeline (measure 100) it worked.
 
I experimented with changing the tempo at measures 90, 80 & 70. The closer I got to 65, the more clips got messed up. Most of my clips are in the measure 50-65 area. So I'm thinking the problem has something to do with making a tempo change near an area with a lot of V-vocal clips.
 
Big thanks, you've set me in the right direction I think. I'll keep experimenting, and worst case I'll render all my V-vocal clips. I'll let you know how it goes!

Haha, well your suggestions led me to a decent workaround for now. Since I can make the tempo change at measure 100, I did that. Then I tried to delete all the measures between measure 65 (where I want the tempo change) and 100. That didn't work, it messed up the clips. So instead, at measure 65 I changed the meter from 4/4 to the smallest value, 1/32. So those 35 measures whiz by in about 2 seconds.
 
To fill those 2 seconds, I just let a chord ring out extra long before the next part of the song which is now at the new tempo I wanted. Not ideal, but it works. Cheers!