Microsoft has confirmed an issue causing Windows 7 to delete System Restore Points on reboot. According to the Redmond comapny "Upon each reboot, Windows 7 may delete all System Restore Points. This issue can occur if the system paging file is highly fragmented," explained Microsoft in KB2533911 article.
However, Microsoft did advise customers impacted by the issue to disable, delete and then recreate the paging file. To do this, carry out the following steps:
1. Open Control Panel and type 'advanced system settings' in the search box. Click the link for 'View advanced system settings'.
2. On the Advanced tab, click 'Settings' under Performance.
3. On the Advanced tab, click 'Change...' under Virtual Memory.
4. Select the entry for drive C: and select the radio button labelled 'No paging file', then click the Set button.
5. Click 'Ok' three times to exit out of the system properties dialogs, then reboot.
6. Delete 'pagefile.sys' from the root of C: drive. Note: pagefile.sys is a hidden file and is not visible until you set the folder option to view hidden files.
7. Defragment the C: volume. From an elevated CMD prompt, run 'defrag /h c:'.
8. Reenable the paging file by following steps 1-3 above.
9. After selecting drive C: in the dialog, select the radio button for 'System managed size' and click Set. You can also select 'Custom size' if you wish to make a pagefile of a specific size.
Note: selecting 'Custom size' and setting both 'Initial size' and 'Maximum size' to the same value will result in a statically sized paging file. This can help mitigate fragmentation of the paging file in the future.
10. Click 'Ok' three times to exit out of the Advanced System Properties dialogs and reboot.