in explorer (not IE): service -> properties -> file types -> you image type -> i need all actions for file

also you can uninstall psp and use registry cleaner (such as vit registry fix) and then install psp, but i'm not sure this will work.

This?

Yes.

Absolutely crazy. When I click on any image, PSP opens and I get this:
Never saw such thing. It says Windows can't find the file path.

remove dde. i had that problem with swfs when i recover after opera

Can't. I uncheck it, click ok, close, get back, it is checked again...

try to deactivate kaspersky or load in safe mode

In safe mode, I can't disable dde neither. The only difference in safe mode was that PSP could find the path to the files (not always, but often) and open them.
Files properties have a new thing which they had not before. It says that they come from another computer and are blocked for security reasons. I guess some thing in security system was changed by Infium. Kaspersky did not block them.
What could be the reasons that an .exe file stops to work suddenly? (process is show, but does not open)

go to regedit -> HKEY_CLASSES_ROOT -> .jpg
what do you see?

I modified them to open with Windows viewer so I see:

jpg/open with list/ois.exe/Pictureviewer.exe/Open with progids/persistent handler

bmp/open with list/MsPaint.exe/ois.exe/Pictureviewer.exe/Open with progids/persistent handler

no, keys in .jpg

This? want binary values from inside?

HKEY_CLASSES_ROOT -> jpegfile
can you export this section and post here?

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\jpegfile]
@="Image JPEG"
"EditFlags"=dword:00010000
"FriendlyTypeName"=hex(2):40,00,25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,\
    00,6f,00,6f,00,74,00,25,00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,\
    32,00,5c,00,73,00,68,00,69,00,6d,00,67,00,76,00,77,00,2e,00,64,00,6c,00,6c,\
    00,2c,00,2d,00,33,00,30,00,33,00,00,00
"ImageOptionFlags"=dword:00000003

[HKEY_CLASSES_ROOT\jpegfile\CLSID]
@="{25336920-03F9-11cf-8FD0-00AA00686F13}"

[HKEY_CLASSES_ROOT\jpegfile\DefaultIcon]
@="shimgvw.dll,3"

[HKEY_CLASSES_ROOT\jpegfile\shell]

[HKEY_CLASSES_ROOT\jpegfile\shell\Convert image format...]
@=""

[HKEY_CLASSES_ROOT\jpegfile\shell\Convert image format...\command]
@="\"C:\\PROGRA~1\\AMAZIN~1\\Amazing Photo Editor.exe\" \"%1\" Convert"

[HKEY_CLASSES_ROOT\jpegfile\shell\Edit image...]

[HKEY_CLASSES_ROOT\jpegfile\shell\Edit image...\command]
@="\"C:\\PROGRA~1\\AMAZIN~1\\Amazing Photo Editor.exe\" \"%1\" Edit"

[HKEY_CLASSES_ROOT\jpegfile\shell\open]
"MuiVerb"="@shimgvw.dll,-550"

[HKEY_CLASSES_ROOT\jpegfile\shell\open\command]
@="rundll32.exe C:\\WINDOWS\\system32\\shimgvw.dll,ImageView_Fullscreen %1"

[HKEY_CLASSES_ROOT\jpegfile\shell\open\DropTarget]
"Clsid"="{E84FDA7C-1D6A-45F6-B725-CB260C236066}"

[HKEY_CLASSES_ROOT\jpegfile\shell\printto]

[HKEY_CLASSES_ROOT\jpegfile\shell\printto\command]
@="rundll32.exe C:\\WINDOWS\\system32\\shimgvw.dll,ImageView_PrintTo /pt \"%1\" \"%2\" \"%3\" \"%4\""

hm... i don't know