Major/noticeable changes to version 2018.05.01.
The emulated CPU is up to 40% faster, though less in protected mode operation.
Record locking was validated every host OS granted request, while an one-time-only confirmation per drive is conclusive. It slowed down multi-user database programs, especially when accessing network hosted files.
Text copy/paste is now [Ctrl+Win+]left/right mouse click; Ctrl+Win+C/V are used by Windows itself since the Fall Creators Update.
Simplified configuration by dropping directives from config.txt: "FRAME=" (window is always bordered), "XMEM=" (10MB of both XMS and EMS memory is provided), "LINS=" and "COLS=" (replaced by TEXT=<lins>x<cols>, "WINKEY=", and "EURO=". Added "CTRL+V=" to en/disable this pasting option.
Dropped global "TIMEOUT=" config.txt directive in favor of "TIO:<seconds>" per print device. Added default line character substitution for "---" and "===" sequences.
F-Keys repeat, fixed pasting text in Clipper (now a bit slower in all apps).
More accurate BIOS timer tick, servicing routines. Those were postponed and could even miss a tick. Added dedicated idle detection for protected mode operation.
'Only' 16,384 memory address relocations were supported with .EXE files, if smaller than 480 bytes, they were not loaded. If the SP was 0xfffe, a RETF instruction didn't cause the SP to wraparound. REP LODSx (silly to repeat of course) with the DF flag set, returned the value of an incorrect memory address.
The SFN filter is removed from file listings.
More comprehensive logging for troubleshooting ("...vDos.exe" /log).
Switched development to Visual Studio 2017. Its "Favor Speed" optimizing option actually favors "Size" sometimes, resulting in smaller, but slower code.
vDos now comes in a 100% open source Base version, basically the 2017.08.01 version, w/o printing and executing Windows programs. These are closed source, as are further developments. vDosSetup will install the Base version and patch it to version 2018.05.01 if selected.
Download vDos: Installation program 2018.05.01 (1.4 MB) | Source files or older versions
First read the little documentation vDos has to offer to make it run your application! Keep in mind you once had to configure DOS, the transition to Windows (XP?) took time. You forgot about that…

Have a look at the FAQs and Forum pages, eventually post your question/problem on the latter. The forum is monitored by Edward Mendelson and me, replies are mostly real quick.
If your issue however seems real specific to your situation/application, or you don’t want it public: Send an email to (change the "a" to an "o").

Submitting a problem or issue: Describe it as detailed as possible, eventually attach your autoexec and config.txt files. If your autoexec.txt starts another batch file, include that also. A mere “My DOS program won’t …” doesn’t help to come to a solution, how simple that might be...