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This is definitely a signal issue. This indicates that the return signal from your box is not working properly and your SDV channels are not being requested from the head end.
Here's additional information on the signal topic (link below). Lazy technicians who don't want to go to the trouble of properly diagnosing the problem, as stated by @Gdkitty. VOD not working properly is also an indicator as he mentioned.
No, however, if your unit is rebooting at that time, you can set a series recording, say of one of the Stingray channels for that time and the box won't reboot at that time. This assumes you have a PVR. The Stingray channels take up very little hard drive space and you can then delete them once a week or so.
This (rebooting) issue seems to affect some boxes but not others. Here's a link to tips, issues, etc: