I experienced the same bug that happened in FASMW v1.46 on lodsb when esi=07 with newest FASMW v1.46.9.4!
State Dump for Thread Id 0x49c
eax=00000007 ebx=0041b61b ecx=00000100 edx=00000000 esi=00000007 edi=00406320
eip=0040c85b esp=0006fe20 ebp=0006fe2c iopl=0 nv up ei pl zr na po nc
cs=001b ss=0023 ds=0023 es=0023 fs=0038 gs=0000 efl=00000246
function: <nosymbols>
0040c83f c21400 ret 0x14
0040c842 c8000000 enter 0x0,0x0
0040c846 53 push ebx
0040c847 56 push esi
0040c848 57 push edi
0040c849 8b7508 mov esi,[ebp+0x8] ss:00b0d3fe=????????
0040c84c 8b7d0c mov edi,[ebp+0xc] ss:00b0d3fe=????????
0040c84f bb1bb64100 mov ebx,0x41b61b
0040c854 b900010000 mov ecx,0x100
0040c859 31d2 xor edx,edx
FAULT ->0040c85b ac lodsb ds:00000007=??
0040c85c 3c20 cmp al,0x20
0040c85e 7434 jz 00410494
0040c860 3c3b cmp al,0x3b
0040c862 0f8481000000 je 0040c8e9
0040c868 88c4 mov ah,al
0040c86a d7 xlat
0040c86b 08c0 or al,al
0040c86d 7454 jz 0040d1c3
0040c86f 09d2 or edx,edx
0040c871 7519 jnz 0041488c
0040c873 80fc27 cmp ah,0x27
*----> Stack Back Trace <----*
FramePtr ReturnAd Param#1 Param#2 Param#3 Param#4 Function Name
0006FE2C 00408FE6 00000007 00406320 00C30288 00000019 !<nosymbols>
0006FF00 77E12E98 006003E0 00000100 00000026 01480001 !<nosymbols>
0006FF20 77E130E0 00407000 006003E0 00000100 00000026 user32!ScrollDC
0006FFAC 77E15824 00405FA0 00000001 00409ED8 00405FA0 user32!ScrollDC
0006FFF0 00000000 00409C7C 00000000 000000C8 00000100 user32!DispatchMessageA
*----> Raw Stack Dump <----*
0006fe20 20 64 40 00 ff ff ff ff - 28 0e c3 00 00 ff 06 00 d@.....(.......
0006fe30 e6 8f 40 00 07 00 00 00 - 20 63 40 00 88 02 c3 00 ..@..... c@.....
0006fe40 19 00 00 00 e8 0b c3 00 - b8 8b 40 00 50 95 07 00 ..........@.P...
0006fe50 a0 5f 40 00 a8 5f 40 00 - 00 00 00 c0 00 00 79 00 ._@.._@.......y.
0006fe60 35 01 30 50 08 01 79 00 - c3 00 00 00 98 d9 f3 00 5.0P..y.........
0006fe70 06 00 00 00 8e 00 00 00 - 18 87 79 00 00 00 00 00 ..........y.....
0006fe80 83 00 00 00 00 00 00 00 - 06 00 00 00 8f 00 00 00 ................
0006fe90 00 00 00 00 77 0c 0a a0 - 07 00 00 00 0e 00 00 00 ....w...........
0006fea0 1e 00 00 00 48 00 c3 00 - 60 00 00 00 1f 00 00 00 ....H...`.......
0006feb0 ff ff ff 00 00 00 00 00 - 00 16 2d 00 ff ff ff 00 ..........-.....
0006fec0 42 c8 40 00 c8 13 40 00 - e8 04 f4 00 00 08 f4 00 B.@...@.........
0006fed0 00 08 7a 00 58 f2 79 00 - 00 00 00 00 00 00 00 00 ..z.X.y.........
0006fee0 2a 00 00 00 9a 00 00 00 - 00 00 00 ff 7e fb e1 77 *...........~..w
0006fef0 00 00 00 00 26 00 00 00 - 01 00 48 01 00 b6 00 04 ....&.....H.....
0006ff00 20 ff 06 00 98 2e e1 77 - e0 03 60 00 00 01 00 00 ......w..`.....
0006ff10 26 00 00 00 01 00 48 01 - a8 5f 40 00 cd ab ba dc &.....H.._@.....
0006ff20 ac ff 06 00 e0 30 e1 77 - 00 70 40 00 e0 03 60 00 .....0.w.p@...`.
0006ff30 00 01 00 00 26 00 00 00 - 01 00 48 01 1b b6 41 00 ....&.....H...A.
0006ff40 a2 0f 41 00 00 00 00 00 - 74 ff 06 00 01 00 48 01 ..A.....t.....H.
0006ff50 58 4a e2 77 00 00 00 00 - 00 00 00 00 04 00 00 00 XJ.w............
State Dump for Thread Id 0x4f8
eax=77d50c62 ebx=00c35798 ecx=00c35654 edx=00000000 esi=00c35698 edi=00000100
eip=77f82a84 esp=00d4fe28 ebp=00d4ff74 iopl=0 nv up ei pl nz na pe nc
cs=001b ss=0023 ds=0023 es=0023 fs=0038 gs=0000 efl=00000202
function: ZwReplyWaitReceivePortEx
77f82a79 b8ac000000 mov eax,0xac
77f82a7e 8d542404 lea edx,[esp+0x4] ss:017ed3fb=????????
77f82a82 cd2e int 2e
77f82a84 c21400 ret 0x14
*----> Stack Back Trace <----*
FramePtr ReturnAd Param#1 Param#2 Param#3 Param#4 Function Name
00D4FF74 77D50781 77D50D7F 00C35698 00000000 40C351A4 ntdll!ZwReplyWaitReceivePortEx
00D4FFA8 77D50C7A 0007F590 00D4FFEC 77E8758A 00C35798 rpcrt4!RpcBindingSetOption
00D4FFB4 77E8758A 00C35798 00000000 40C351A4 00C35798 rpcrt4!RpcBindingSetOption
00D4FFEC 00000000 77D50C62 00C35798 00000000 00905A4D kernel32!SetFilePointer
*----> Raw Stack Dump <----*
00d4fe28 2d 09 d5 77 00 01 00 00 - 54 ff d4 00 00 00 00 00 -..w....T.......
00d4fe38 58 7d c3 00 58 ff d4 00 - f0 c0 07 00 90 f5 07 00 X}..X...........
00d4fe48 98 57 c3 00 d0 0c 45 80 - 34 00 00 c0 40 df 47 81 .W....E.4...@.G.
00d4fe58 71 36 4a 80 98 88 00 e1 - b0 3c a1 be 98 88 00 e1 q6J......<......
00d4fe68 00 00 00 00 00 00 00 00 - 46 02 00 00 68 10 45 80 ........F...h.E.
00d4fe78 01 00 00 00 40 df 47 81 - 00 00 00 00 10 00 f8 00 ....@.G.........
00d4fe88 0a df 12 81 7c 00 f8 00 - 1a df 12 81 88 1e 48 81 ....|.........H.
00d4fe98 98 88 00 e1 00 00 00 00 - 1f 00 00 00 f0 1e 48 81 ..............H.
00d4fea8 f0 1e 48 81 00 00 00 00 - 01 00 00 00 10 3c a1 be ..H..........<..
00d4feb8 00 00 00 00 f8 d8 4a e2 - d4 3b a1 be 00 00 00 00 ......J..;......
00d4fec8 91 4e 41 80 f0 1f 48 81 - 40 df 47 81 c4 3c a1 be .NA...H.@.G..<..
00d4fed8 a8 04 45 80 04 00 00 00 - 08 df 12 81 97 db 49 80 ..E...........I.
00d4fee8 80 f3 12 00 00 00 00 00 - 48 f3 12 00 d5 82 42 00 ........H.....B.
00d4fef8 00 00 00 00 00 00 00 00 - 01 00 00 00 19 00 02 00 ................
00d4ff08 64 27 50 c0 7a 00 00 00 - 00 00 00 00 00 00 00 00 d'P.z...........
00d4ff18 7a 00 00 00 01 00 00 00 - 00 20 50 c0 40 db 1a 81 z........ P.@...
00d4ff28 00 14 17 81 a0 eb 0c 81 - 20 b0 11 81 00 00 00 00 ........ .......
00d4ff38 b0 b1 11 81 60 3c a1 be - 46 02 00 00 ec d8 42 80 ....`<..F.....B.
00d4ff48 c0 95 06 80 80 b1 11 81 - 20 b0 11 81 00 20 50 c0 ........ .... P.
00d4ff58 00 a2 2f 4d ff ff ff ff - 50 fe d4 00 ff ff ff ff ../M....P.......