plot failed with: fopen() failed

[Bonejeezy]

I am currently running madmax v0.1.6 and after 9 plots are created the 9th plot or 10th plot will throw up this error plot failed with: fopen() failed for H:\ChiaPlots\ and then the drive is unable to be open in windows and throws an I/0 error sorry don't have the specific one. I thought it was because the external 18tb seagate drive was not formatted to ntfs but but i did a reformat to ntfs and I still get that error after 10 plots? any suggestions what I could be doing wrong?

[Bonejeezy]

I am running 3900x with 64gb gb ram 3600mhz -r 20 -u 256