vmu's keep switching on when i turn my dreamcast off

[deded]

i recently fitted batteries to my dreamcast vmu's which had all been dead for years, but sometimes now when i switch off the dreamcast the vmu's will beep and turn on and be on the main menu of the vmu, either this or it will completely reset and be sat there asking me for the date and time, which is yeah, only a minor niggle but its beginning to **** me off now after a few weeks of having to manually unplug the vmu's and setting them to sleep and putting them back again when finished playing

any ideas why this might be happening?

cheers,
bren

[deded]

HOLIHOCKS!