If you suspect the POOL have you tried to ask this question to them?
Do you see a "Dev Fee" during the time of those "hacks" ?
Please provide screenshots.
[/quote]

Sorry, I have got mistake, I downloaded Claymore v9.7 from this web:

http://worldvision.vn/U1/huong-dan-su-dung-tool-cay-coins_c93/huong-dan-va-dowload-tool-cay-coin-claymore-ethereum-9-7--eth--all-phien-ban_c215.htm

And unfortunately, they already modified dpool.txt and epool.txt to lead the pool to their wallet without any announcement to user.

I've replaced that one with pool which downloaded from bitcointalk.org. I think everything will be fine.