Xubuntu install on Win7 laptop fails

[MR ZenWiz]

I have a Lenovo ThinkPad at work where we are required to have Windows
on the machine. I shrank the Windows partition so I could install
Xubuntu 16.04.2 and run with that without destroying the Windows
installation.  I used my 16Gb Patriot flash drive (even though this is
the one that gave me headaches with my own laptop and never did boot
Xubuntu there, though it runs fine as a live boot - I'll be replacing
that image soon...).

Everything appeared to go well and the install finished, but when I
rebooted, the machine came up part way in Windows, then began flashing
through the RGB colors on the monitors. I never saw the grub menu or
had the option to bring up Xubuntu.  There were no error messages,
just the colors.

I had to cycle the power and tell it to boot up normally (from the
Windows safe boot options screen).

This is another first.  I'm thinking of running gparted from my
gparted flash drive to see what's going on, but I'm hesitant to do too
much since it is, after all, a work machine, not my own.

Suggestions welcome.

MR