Small "black line" beside upload symbol

At random intervals during an upload, I get a vertical & curved black line beside the "uploading" icon. The uploading icon is a grey hard disk, with a green arrow coming off it, yeah? Well, randomly, a thin black curved line appears beside the green arrow.

Anyone know what this means?

Thanks.

I just managed to get a screenshot of it moments ago when it appeared:

Image

Please post the system information from the menu: Help->About "System Information"

It is probably a small drawing error you can ignore.

Regards,
Mat

+- System -----------------------------
Microsoft Windows XP Professional
Service Pack 2 (Build 2600)

CPU Speed : 2216 MHz
Total Memory : 1535 MB
Free Memory : 579 MB

+- SmartFTP ---------------------------
Version : 2.0.1002.0
Time Stamp : 2007-01-21 12:39:34
Platform : x86

+- Application DLL --------------------
sfFTPLib.dll : 1.5.9.4
SmartHook.dll : 1.0.2.1

+- Language ---------------------------
SmartFTP.exe : 2.0.1002.0

+- System DLL -------------------------
unicows.dll : 1.0.4018.0
shell32.dll : 6.00.2900.3241 (xpsp_sp2_qfe.071025-1245)
shlwapi.dll : 6.00.2900.3059 (xpsp_sp2_qfe.070104-0040)
comctl32.dll : 6.0 (xpsp.060825-0040)
riched20.dll : 5.30.23.1228
schannel.dll : 5.1.2600.3126 (xpsp_sp2_gdr.070425-0226)

+- Internet Explorer ------------------
Version : 7.0.5730.11

+- Winsock ----------------------------
Winsock : 2.2se