This a new install. I'm using grbl Ver 1.1 and UGS 2.0. Just trying to cut a simple circle. G Code from CamBam. ( Made using CamBam - CamBam CNC Software ) ( Circle 2 Test 2/17/2019 9:09:29 AM ) ( T0 : 0.25 ) G20 G90 G64 G40 G0 Z0.125 ( T0 : 0.25 ) T0 M6 ( Profile1 ) G17 M3 S1000 G0 X2.125 Y0.0 G0 Z0.0625 G1 F10.0 Z-0.5 G3 F30.0 X-1.0625 Y1.8403 I-2.125 J0.0 G3 Y-1.8403 I1.0625 J-1.8403 G3 X2.125 Y0.0 I1.0625 J1.8403 M5 M30 When I send I get this message. System starts and runs normal even without clearing above message. When I get to this point (shown below) UGS stops sending code. If I click SEND again code sending resumes. If I do a double pass the second pass goes without a problem. Below is text from Console window. Lock up point is indicated. [MSG:Caution: Unlocked] ok Skipping command #3 Skipping command #4 Skipping command #5 >>> G20 >>> G90 >>> G64 >>> G40 ok >>> G0Z0.125 Skipping command #11 >>> T0 >>> M6 Skipping command #14 >>> G17 >>> M3S1000 >>> G0X2.125Y0.0 >>> G0Z0.0625 Skipping command #19 >>> G1F10.0Z-0.5 >>> G3F30.0X-1.0625Y1.8403I-2.125J0.0 ok (error:20) Unsupported or invalid g-code command found in block.(error:20) Unsupported or invalid g-code command found in block. ok ok ok (error:20) Unsupported or invalid g-code command found in block.(error:20) Unsupported or invalid g-code command found in block. ok ok ok ok ok ok LOCKS AT THIS POINT click SEND **** Resuming file transfer. **** >>> G3Y-1.8403I1.0625J-1.8403 >>> G3X2.125Y0.0I1.0625J1.8403 >>> M5 Skipping command #25 ok ok **** Finished sending file in 00:07:03 **** ok Another thing What is all the Skipping commands about? I can get my part cut but not knowing what is going on is troubling. Thanks for the help.