scitex dolev 800v communication error

Scitex psm 7.0 + SFL + VLSI when we start expose out of 2-3 films we get stop spiral overflow error, then we start expose some other files also same problem ...

Then we changed the fibre optics port in the VLSI 2 days no issues again from saturday onwards error stats that stop spiral overflow..

Today we changed the fibre optics same error ; we changed the VLSI same error.. we didnt have SFL we couldn't test SFL

The error as below : Layoutplot_set start Expose Flat.jt
Plotter set commproblem error -227
DC : Total elapsed time :14 sec

sometime getting the error
The error as below : Layoutplot_set start Expose Flat.jt
General Set System error - 5244
Plotter set commproblem error -227
DC : Total elapsed time :14 sec

Finally we tried to swap VLSI + SFL into TSP getting new error

Couldnt expose the job memory low: quit some application to expose.. apart from psm no other appication is launched..

256 mb ram available.. 40 gb hard disk..

Exposing file type 1 bit tiff for both tsp / vlsi and sfl

Any suggestions

regards
kala