error: "Unauthenticated", code: -1
Hello, 

I am using xmrig-amd to mine at supportXMR.com. I do use other versions of XMRig for CPU mining at lower hashrates but only on xmrig-amd I get occcationally the following error:

> [2018-03-25 13:22:10] [pool.supportxmr.com:7777] error: "Unauthenticated", code: -1
> [2018-03-25 13:22:10] no active pools, stop mining

The Radeon manages to get around 150 H/s steady and even on port 7777 the pool sets the difficulty to somwhere between 5000 and 7000. So xmrig-amd sends around 4 to 6 shares per minute. 

The stange thing is, that this error appears sometimes after a few minutes, sometimes after an hour and sometimes after 20h+ 

I had keepalive set to true and now do a "test" run with "false". 

Can anyone chat some light onto this - is the a bug? 

PS: the version I use is: 

> XMRig 2.5.0
>  built on Mar 14 2018 with MSVC 2017
>  features: x86_64 AES-NI
> 
> libuv/1.19.2
> libmicrohttpd/0.9.58

PPS: I see a new version came out 2h ago - so was this a known issue on 2.5.0? 