[plt-scheme] bug in my DrScheme, version 372, English

After starting DrScheme, version 372, English on
Windows XP Professional Service Pack 2, when I go to
Help -> Check for Updates..., the following error
dialog box pops up:

----- error message follows immediately after this
line -----
PLT Version Check

Error: could not connect to website
(tcp-read: error reading (Unknown error; errno=10054))
----- error message ends immediately before this line
-----

Also, when I attempt to try out tetris.ss on PLaneT
with (require (planet "tetris.ss" ("dvanhorn"
"tetris.plt" 1 0))), the following error message
appears:

----- error message follows immediately after this
line -----
require: PLaneT could not find the requested package:
Server had no matching package: Your version of PLT
Scheme is too old to run the specified package in:
(planet "tetris.ss" ("dvanhorn" "tetris.plt" 1 0))
----- error message ends immediately before this line
-----

These bugs started appearing after I noticed that
DrScheme was running extremely slow one day, and then
tried reinstalling DrScheme.  I noticed that DrScheme
was not listed in the "Add/Delete Programs" program in
the Windows Control Panel.

I then reinstalled DrScheme, and the speed returned,
but then I could not update DrScheme from the menu.

I just tried reinstalling DrScheme.  This time,
DrScheme appeared correctly in the "Add/Delete
Programs" program in the Windows Control Panel, and it
seemed that I was able to uninstall and reinstall
DrScheme, version 372, English, correctly; however,
DrScheme still does not seem able to update itself or
to fetch tetris.ss from PLaneT.

What should I do?

Benjamin L. Russell