False Reading on "Get Info"

Do you want me to erase the flashdrive first? You know it thinks it's full.

I copied 132 MB of pictures on to the SanDisk and the Get Info showed 140 MB. Then I copied 57 MB of other documents and the SanDisk showed 203 MB stored on it. Then I went over to the XP side and copied 41 MB of files. The new total was 244 MB. And the pie chart under Properties looked normal. There were no problems with any of this. Maybe there IS a problem of some kind with the files I was originally trying to copy onto the flashdrive.
But I could access any or all of them, making changes if desired, when they were in My Documents on both my old Win98 and the XP side of my new iMac. There was no corruption in any of them so far as I know. All were MS Word documents with embedded pictures.

The files I have been trying to transfer to the flashdrive have been texts to art songs and opera libretti, 170-180 files. (I mistyped earlier when I said 111 files.) Most of these are the files I had on floppies, and at one time had in My Documents. Working in XP, I copied the contents of 9 floppies to a folder on the desk top. Some of the texts were in the old format of Word 6.0/95, so I resaved each file to the folder in XP Word. I plugged in the erased SanDisk, highlighted all the files in the folder and dragged them en masse to the flashdrive, for 13.1 MB, about right for 9 full floppies. Five files would not transfer - Herbert, Humperdinck, Ives A, Ives B and J. Strauss. The alphabetically arranged files before and after these five loaded fine. These files generated the message that the “directory or file cannot be created.” I tried dragging the five individually, but got the error message each time.
I plugged in an empty 128 MB Memorex flashdrive and did the same thing. This time also, five files did not transfer, generating the same error message. but they were different - Dvorak, Elgar, Falla A, Falla B and Gershwin. The afore mentioned five loaded OK on this drive. And again, the files before and after these latter five loaded fine, for 12.9 MB Then I plugged in both flashdrives and tried to copy the Herbert, Humperdinck, Ives A, Ives B and J. Strauss files from the Memorex to the SanDisk, but got the error message again. The same thing when I tried to drag the other five from the SanDisk to the Memorex.
So I went to the OS X side and plugged in both flashdrives. You'll recall that the Herbert file was one of the files that loaded on the Memorex but not on the SanDisk. Get Info on the Herbert showed 264 KB. I tried to drag the Herbert from the Memorex - where it had loaded successfully on the XP side - to the SanDisk where it had previously failed. I got the message “The item 'Herbert - Naughty Marietta' cannot be copied because there is not enough free space.” But Get Info on the SanDisk showed 14.2 MB used; 1.9 GB available.
I tried the same thing with the Dvorak file (64 KB) from the SanDisk to the Memorex drive and got the same “not enough free space” message even though Get Info on the Memorex showed 13 MB used, 111 MB available.
I guess two basic questions remain before us:
(A) Why would some files transfer from the desktop folder to one flashdrive, but not the other, with the difficulties lying in different files for the two different drives?
(B) Why do the flashdrives think they are full (or the computer think they are full) when only a very small portion has actually been used?

These are all MS Word files I have personally typed.
I have been collecting and listening to so-called classical music for over 50 years and I have a large library of song/opera texts going back to typewriter days.

In XP, I opened the Humperdinck document from the folder I had created on the desktop from the floppies. I then opened a new blank MS Word document, copied the Humperdinck file to the clipboard and then pasted it into the new blank document. I saved that to My Documents under another name. "Properties" confirmed the file size of this newly saved document to be the correct 168 KB. I then did a Save As to the SanDisk. I immediately got the error message, "Word cannot save or create this file. Make sure that the disk you want to save the file on is not full, write-protected or damaged." The computer still thinks this flashdrive is full even tho 1.9 GB are free and the "Properties" pie chart shows only a line to represent the 14.2 MB stored there. And rightfully so, since the 14.2 MB previously placed on the disk represent such a tiny portion of the nearly 2 GB capacity.
I think this is what you were suggesting, but it did not help. I looked at the document closely. It is nothing but typed text.

Yes

Yes,Parallels
Oh, and I tried something else. This morning I received a picture attached to an email. I wanted to massage it with Photoshop Elements 2 which I keep on the XP side because I understand that this early version of Photoshop is not compatible with OS X. I was going to put the picture - an ordinary jpeg - on the SanDisk and then extract it when running XP. The picture would not load to the flashdrive; I got the old "not enough free space" message even tho Get Info shows 1.9 GB available.

Yeah, but I get my mail through Thunderbird on the OS X side. I was in OS X when I tried unsuccessfully to put the picture on the SanDisk. I had to use yet another flashdrive to put the picture on, and then use that drive over on XP to use Photoshop.
I don't know what "check your Parallels settings for USB" means.