diff --git a/managing-os/windows-tools-3.md b/managing-os/windows-tools-3.md
index ae65bb24..16d2524c 100644
--- a/managing-os/windows-tools-3.md
+++ b/managing-os/windows-tools-3.md
@@ -32,6 +32,8 @@ Qubes Tools for Windows (QTW for short) contain several components than can be e
 
 **In testing VMs only** it's probably a good idea to install a VNC server before installing QTW. If something goes very wrong with the Qubes gui agent, a VNC server should still allow access to the OS.
 
+**NOTE**: Xen PV disk drivers are not installed by default. This is because they seem to cause severe problems, including disk image/files corruption in Qubes HVMs. We're investigating this. *However*, the problem doesn't always occur in tests -- disk drivers often work *if they are installed separately after the main portion of QTW is up and running*. **Do this at your own risk** of course, but we welcome reports of success/failure in any case. With disk PV drivers absent `qvm-block` will not work for the VM, but you can still use standard Qubes inter-VM file copying mechanisms.
+
 Verbose installation
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