Background Jobs getting Cancelled

Hi SRM Gurus

we are working on SRM 4.0 and follow a classic scenarios.

We have schedulled following background jobs

1 BBP_GET_STATUS_2

2 CLEAN_REQREQ_UP

3 SMWP_BATCH

Which were running successfully however from yesterday this all jobs are showing status cancelled.

Can any one throw some light as to why this jobs are getting cancelled or how to check the reaons for the cancelling of jobs.

regards,

Nimish Sheth