Vista doesn't "want to" create restore points anymore

System Restore Symptoms:
- Vista 64 SP2 Home Premium, no dual boot
- 136 GB free on system hard drive (C). 
- vssadmin list shadowstorage => Used 0 / Allocated 0 / Maximum 40GB
- vssadmin list providers => no errors (see bottom)
- vssadmin list writers => no errors (see bottom)
- vssadmin list volumes => C and D (see bottom)
- Services: Windows Backup service and Volume Shadow Copy are on automatic. Windows Backup shows "started", but VSS does seem not start by itself. I tried starting it to create a restore point. It starts, but later on I see that it has stopped again.
- System Restore is enabled on my system drive (just in case something was corrupted, in System Protection I unchecked C (system), applied, rechecked, applied).
- When I click Create in "System Protection" => "The restore point was created successfully".
- When I click "Restore" (not in order to restore, but to see if a restore point was in fact created) => "No restore points have been created".
- vssadmin list shadows => "No items found that satisfy the query"
- Since yesterday the free space on my hard disk has jumped up by about 40GB, which is the maxium size for VSS
- sfc/scannow => no "cannot repair" related to VSS (the only "cannot repair" error in C:\Windows\Logs\CBS\CBS.log has to do with tcpmon.ini). 
- tried resizing to 10GB then back to 40GB: "vssadmin resize shadowstorage /on=c: /for=c: /maxsize=10GB". No error resizing, but restore points are still not created.
- sc queryex vss => Stopped. (I can start it, but it stops again).
- Task Scheduler / System Restore / SR / Properties: 
---> Conditions are fine (unchecked "start only if the computer is idle for...")
---> Privileges (SYSTEM on highest privileges), Settings and Triggers look fine
---> History: Latest = Task Completed ("Task Scheduler succesfully finished"), the task had been triggered by computer startup.
- vssadmin list providers => no errors (see bottom)
- vssadmin list writers => no errors (see bottom)
- vssadmin list volumes => C and D (see bottom)
 
C:\Users\owner\Desktop>Vssadmin List Providers
vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001-2005 Microsoft Corp.
 
Provider name: 'Microsoft Software Shadow Copy provider 1.0'
   Provider type: System
   Provider Id: {b5946137-7b9f-4925-af80-51abd60b20d5}
   Version: 1.0.0.7
 
 
C:\Users\owner\Desktop>vssadmin list writers
vssadmin 1.1 - Volume Shadow Copy Service administrative command-line t
(C) Copyright 2001-2005 Microsoft Corp.
 
Writer name: 'System Writer'
   Writer Id: {e8132975-6f93-4464-a53e-1050253ae220}
   Writer Instance Id: {2b247b2c-e268-4aec-b27b-c952a75918c3}
   State: [5] Waiting for completion
   Last error: No error
 
Writer name: 'ASR Writer'
   Writer Id: {be000cbe-11fe-4426-9c58-531aa6355fc4}
   Writer Instance Id: {f4b2365b-d6aa-41b5-ad66-b5ec78a2a670}
   State: [1] Stable
   Last error: No error
 
Writer name: 'Registry Writer'
   Writer Id: {afbab4a2-367d-4d15-a586-71dbb18f8485}
   Writer Instance Id: {b3190373-b60a-4f40-a957-491e14c16f96}
   State: [1] Stable
   Last error: No error
 
Writer name: 'WMI Writer'
   Writer Id: {a6ad56c2-b509-4e6c-bb19-49d8f43532f0}
   Writer Instance Id: {ddfa4613-3691-4e9a-8ad5-a38a0c73572f}
   State: [5] Waiting for completion
   Last error: No error
 
Writer name: 'BITS Writer'
   Writer Id: {4969d978-be47-48b0-b100-f328f07ac1e0}
   Writer Instance Id: {f1a487ba-e8d8-48cc-bb8d-3798e642e376}
   State: [1] Stable
   Last error: No error
 
Writer name: 'Shadow Copy Optimization Writer'
   Writer Id: {4dc3bdd4-ab48-4d07-adb0-3bee2926fd7f}
   Writer Instance Id: {daaae144-3c4c-496b-ac85-ccfc50e670ec}
   State: [1] Stable
   Last error: No error
 
Writer name: 'COM+ REGDB Writer'
   Writer Id: {542da469-d3e1-473c-9f4f-7847f01fc64f}
   Writer Instance Id: {e476ef46-3c13-410e-aef5-3a21005d660f}
   State: [1] Stable
   Last error: No error
 
Writer name: 'MSSearch Service Writer'
   Writer Id: {cd3f2362-8bef-46c7-9181-d62844cdc0b2}
   Writer Instance Id: {3140e57d-c93f-437c-90ed-f395eac5d5fb}
   State: [5] Waiting for completion
   Last error: No error
 
 
C:\Users\owner\Desktop>vssadmin list volumes
vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001-2005 Microsoft Corp.
 
Volume path: D:\
    Volume name: \\?\Volume{15760ab9-696d-11dd-ab44-806e6f6e6963}\
Volume path: C:\
    Volume name: [URL="file://\\?\Volume{15760aba-696d-11dd-ab44-806e6f6e6963}\"]\\?\Volume{15760aba-696d-11dd-ab44-806e6f6e6963}\[/URL]