Show us your circuit! Post the .asc file, if it's not too big. This kind of error usually indicates there's something dodgy in your circuit; something that's likely not to work in a real circuit either.
Look for a reason why the circuit might want to oscillate at some insanely high frequency. This sort of thing tends to happen when you have inadvertantly created an unstable numerical problem for the solver. It tries its best and repeatedly decreases the time step to try and get an accurate solution until it gives up.
Oh dear! A switching power supply. Debugging those is *work*, of which I have quite enough, thank you.
I've spent a few minutes trying to simulate the thing, after having whimsically substituted LT1018s for the comparators, NPN, PNP and PMOS generics for the transistors I don't have the models for (i.e., all of them), and fixing the values of some caps and the coils, which seemed garbled.
I don't see what the circuitry involving Q4 and Q5 with the amplifiers driving them is for either.
The simulation runs without the error you described, but the circuit doesn't work. I'd say, try to increase the PMOS gate series resistor to 50 Ohms and/or insert resistors in the collector leads of the driver transistors. A few tens of ohms might do it.
I'm sorry but I can't afford to put in the time required to go any further.