Assertion failed!
Program: C:\...\cryptonite-qt.exe
File:trieview.cpp, Line 305
Expression: blockCacha.ReadBlockFromDisk(block, pindex)
More info please: did you upgrade or start from scratch? Was the data dir populated already?
Besides: as a general rule, it's wise to BACKUP YOUR PRIVATE KEYS (in some encrypted form). That way, if the wallet db gets corrupted, or is incompatible with a future release (which shouldn't in the case of XCN, but you never know), you can always import the key and get your coins.
I downloaded the wallet from Official Site, launched it (the directory created a new one), it was synchronized for a long time and closed with an error. I restarted it, it waits a bit and produces an error with the error
Assertion failed!
Program: C:\...\cryptonite-qt.exe
File:trieview.cpp, Line 305"
My debug.log https://yadi.sk/i/13lRyzzW3GXNb5