When I open Indexing Options, it says:

4,317 items indexed Indexing in progress. Search results might not be complete during this time.

It's stuck at 4,317 though; no more items have been indexed. Worst of all, SearchIndexer.exe is taking up 100% CPU (well, 50%, but I have a dual core CPU; it's taking up all processing power it can). It is not causing hard drive activity though.

I tried clicking "Troubleshoot search and indexing" at the bottom of the Indexing Options window, but it couldn't find any problem.

I've also tried the repair registry key that several websites suggest; I change HKLM\SOFTWARE\Microsoft\Windows Search SetupCompletedSuccessfully to 0 and restarted the computer, and it apparently repaired because it flipped back to 1, but the same problem continues to occur.

It's reducing the battery life of my laptop and making it really hot so that my fans are running all the time. I've had to disable the Windows Search service. How can I fix this? Do I need to just flat-out reformat my computer?

Update:
I've tried rebuilding a couple times. There's nothing unusual about the locations I have to index, and I don't have any downloads in progress or anything like that. I don't see any reason why it stopped, and I noticed it much too late to do a system restore. At this point, I'm hoping someone will offer up some secret answer that will fix the problem, thus the bounty.

Another update:
I tried starting the service again, just to let it try yet again. It seemed okay at first (Indexing Options showed it operating at reduced speed due to user activity, and the number of files was going up). A while later I checked, and the service had stopped. Event viewer revealed some errors like this:

Log Name:      Application
Source:        Application Error
Date:          2/1/2010 7:34:23 PM
Event ID:      1000
Task Category: (100)
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      ricky-win7
Description:
Faulting application name: SearchIndexer.exe, version: 7.0.7600.16385, time stamp: 0x4a5bcdd0
Faulting module name: NLSData0007.dll, version: 6.1.7600.16385, time stamp: 0x4a5bda88
Exception code: 0xc0000005
Fault offset: 0x002141ba
Faulting process id: 0x13a0
Faulting application start time: 0x01caa39f2a70ec02
Faulting application path: C:\Windows\system32\SearchIndexer.exe
Faulting module path: C:\Windows\System32\NLSData0007.dll
Report Id: b4f7a7ae-0f92-11df-87fc-e5d65d8794c2
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Application Error" />
    <EventID Qualifiers="0">1000</EventID>
    <Level>2</Level>
    <Task>100</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2010-02-02T00:34:23.000000000Z" />
    <EventRecordID>10689</EventRecordID>
    <Channel>Application</Channel>
    <Computer>ricky-win7</Computer>
    <Security />
  </System>
  <EventData>
    <Data>SearchIndexer.exe</Data>
    <Data>7.0.7600.16385</Data>
    <Data>4a5bcdd0</Data>
    <Data>NLSData0007.dll</Data>
    <Data>6.1.7600.16385</Data>
    <Data>4a5bda88</Data>
    <Data>c0000005</Data>
    <Data>002141ba</Data>
    <Data>13a0</Data>
    <Data>01caa39f2a70ec02</Data>
    <Data>C:\Windows\system32\SearchIndexer.exe</Data>
    <Data>C:\Windows\System32\NLSData0007.dll</Data>
    <Data>b4f7a7ae-0f92-11df-87fc-e5d65d8794c2</Data>
  </EventData>
</Event>

If you are having the same error and arrived here from a Google search, please comment or add an answer detailing your progress on this, if any...