After upgrading to firmware 2.7.9, my system experienced a similar problem to what this user experienced.
Immediately following upgrade, any attempts by ISY to communicate with v.33 LampLinc devices resulted in in a "Request Filed" error. V.37 LampLincs and non-LampLinc v.33 devices were unaffected. Additionally, their On Levels and Ramps Rates were reset to 100% and 0.1s, respectively, in all related scenes. I found that I had to remove each device from ISY and relink in order to regain functionality. Fortunately, it affected only 3 devices in a couple of scenes.[/url]