Communication with printer issue

Hi,
During the testing process, simply by connecting to the printer at 115200bds, I encountered lots of errors/resend.
I'm using Repetier Host 1.6.1 and firmware 0.92.8
By the way, same problem appears as well when I'm sending testing commands, which are taking time before being executed.
See following log:

08:37:24.201 : FIRMWARE_NAME:Repetier_0.92.8 FIRMWARE_URL:https://github.com/repetier/Repetier-Firmware/ PROTOCOL_VERSION:1.0 MACHINE_TYPE:Mendel EXTRUDER_COUNT:1 REPETIER_PROTOCOL:3
08:37:24.217 : Printed filament:0.00m Printing time:0 days 0 hours 0 min
08:37:24.217 : PrinterMode:FFF
08:37:24.217 : Error:Wrong checksum
08:37:24.217 : Resend:3
08:37:24.248 : ok
08:37:24.248 : skip 2
08:37:24.248 : ok
08:37:24.248 : Resend: N4 M114*35
08:37:24.248 : Error:Wrong checksum
08:37:24.248 : Resend:3
08:37:24.264 : ok
08:37:24.264 : skip 2
08:37:24.264 : ok
08:37:24.264 : N5 M111 S6*98
08:37:24.264 : Error:Wrong checksum
08:37:24.264 : Resend:3
08:37:24.280 : ok
08:37:24.280 : skip 2
08:37:24.280 : ok
08:37:24.280 : Error:Missing linenumber
08:37:24.280 : Resend:3
08:37:24.280 : N6 T0*60
08:37:24.295 : ok
08:37:24.295 : skip 0
08:37:24.295 : ok



08:37:24.717 : ok
08:37:24.717 : Error:Format error
08:37:24.717 : Error:Missing linenumber
08:37:24.717 : Resend:3
08:37:24.733 : ok
08:37:24.733 : Error:Missing linenumber
08:37:24.733 : Resend:3


08:38:07.607 : Warning: Seems like we missed a ok, got a wait - continue sending.
08:38:07.611 : Error:Format error
08:38:07.611 : Error:Missing linenumber
08:38:07.611 : Resend:22
08:38:07.626 : Resend: N22 M119*26
08:38:07.626 : ok
08:38:07.833 : Resend:22
08:38:07.837 : ok
08:38:08.845 : wait
08:38:09.845 : wait
08:38:10.861 : wait
08:38:10.861 : Warning: Seems like we missed a ok, got a wait - continue sending.
08:38:10.861 : Error:Format error
08:38:10.861 : Error:Missing linenumber
08:38:10.861 : Resend:22
08:38:10.876 : Resend: N22 M119*26
08:38:10.876 : ok
08:38:11.079 : Resend:22
08:38:11.095 : ok

Any recommendation (I didn't try to decrease speed to 1200 bds :-)) ?

Samuel