This error “Schedulable class has jobs pending or in progress” might occur when saving the class after editing it.
This could be due to the reason that there are scheduled jobs related to the class that we are trying to edit or its dependent classes. To resolve the issue, we can abort the jobs manually from Setup->Jobs->Scheduled Jobs.
There is a detailed explanation about this error in the link https://help.salesforce.com/apex/HTViewSolution?id=000004423&language=en_US
P.S. I had got this error recently in Sandbox for one of the class after I modify it, though its dependent class is scheduled and after deleting the corresponding jobs in Setup->Jobs->Scheduled Jobs, I could save the class successfully.