Android Question Astreams_error Adler checksum

[Rusty]

I've successfully transferred millions of files using prefix mode without any problems.
Now all of a sudden, I'm getting Adler checksum errors on the PC side on valid .jpg files.
When I say valid, they are completely normal and open with all image software on both sides, Android device and PC.
However, when the file is successfully received in my PC application, the checksum doesn't match the Adler.value. (Successfully means the file arrives, is written successfully. In this rare case the Adler.value and checksum don't match)
It only happens on extremely rare occasions.
When I stop my Andoid application and then restart it, it will successfully transmit the file in question. (without doing anything to the PC application like start/stop/reboot etc.)
What can possibly be going on when literally a thousand .jpg files send, then "randomly" a valid file fails the checksum/Adler?
Any ideas on what might cause this and suggestions on how to handle this?

ADDED NOTE: One of the files I'm sending is also an SQLite database. Other Services running on the device open/write/close this database. Is it possible I'm trying to send a database that is open? If so, is there a way to know that an SQlite database is being used by another service/app?

Thanks in advance,
Rusty

 

[Erel]

This can happen if the file is modified during the transfer. Is it possible that the image files are being modified? What is the size of the files?

 

[Rusty]

They are size range from 1kb to 1.5mb.
I suppose I could be trying to transfer a file the instant it is being created...
That is possible since I have 2 services running simultaneously one creating these files and another monitoring the folder location in which the files are stored then sending them when they appear...
Rusty