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4294967295 is 2^32-1 (i.e. the largest number that can be represented in 4 bytes). My guess is that somehow, you ended up with -1 notifications (taking away a notification when you had 0?), which the system couldn't display properly (-1 in a signed integer is the same as 4294967295 in an unsigned integer). That's why posting a VM worked, as it added 1 notification to that, bringing it back to 0.