scheduler going backwards in time

[Tan Yuan Sin <eng70202@nus.edu.sg>]

I was running a simulation using the DSR protocol when I encounter these
error messages :
.
.
.
.
ns: scheduler going backwards in time from 242.584536 to 242.551853.
ns: scheduler going backwards in time from 242.585224 to 242.552483.
ns: scheduler going backwards in time from 242.585562 to 242.552831.
ns: scheduler going backwards in time from 242.585736 to 242.552969.
ns: scheduler going backwards in time from 242.586139 to 242.553404.
Assertion failed: rtime >= 0.0, file mac-timers.cpp, line 265

abnormal program termination

Can anyone help me on this. Thank you very much.