Scan registry using the search term avast and remove any avast entries.
Reboot.
Then try a clean install of Avast. My experience is limited to the free version so if you're using the paid version of Avast make sure that you've got license keys sorted out before you go ahead.
My Computer
At a glance
Microsoft Windows 7 Home Premium 64-bit 7601 ...AMD C-60 APU with Radeon(tm) HD Graphics4.00 GBAMD Radeon HD 6290 Graphics
Computer type
Laptop
Computer Manufacturer/Model Number
ASUS
OS
Microsoft Windows 7 Home Premium 64-bit 7601 Multiprocessor Free Service Pack 1
CPU
AMD C-60 APU with Radeon(tm) HD Graphics
Motherboard
ASUSTeK COMPUTER INC. X501U
Memory
4.00 GB
Graphics Card(s)
AMD Radeon HD 6290 Graphics
Sound Card
(1) AMD High Definition Audio Device (2) Realtek High Defi
I have exactly the same problem but have never installed any antivirus software. I had to recover my OS installation - following Dell customer services instructions - and after that I came up with 2 Program Files folder (and of course plus the x86 one).
I gonna look for a solution on the web. If for some reason you know how to solve it, please let me know.
This can happen due to spelling/syntax errors in the installer.
There was a program I used to use 4 or 5 years ago that would create erroneous folders, due to someone forgetting to include a path separator (\) in a path name.
My Computer
At a glance
W7 Ultimate SP1, LM19.2 MATE, W10 Home 1703, ...AMD Phenom II x6 1100T, 3.3 GHz12GB DDR3 1333 G-Skill (4GB x 2), G-Skill (2G...NVIDIA GeForce GTX 660
Computer type
PC/Desktop
Computer Manufacturer/Model Number
n/a
OS
W7 Ultimate SP1, LM19.2 MATE, W10 Home 1703, W10 Pro 1703 VM, #All 64 bit
CPU
AMD Phenom II x6 1100T, 3.3 GHz
Motherboard
ASUS M4A88T-M/USB3 (AM3)
Memory
12GB DDR3 1333 G-Skill (4GB x 2), G-Skill (2GB x 2)
Graphics Card(s)
NVIDIA GeForce GTX 660
Sound Card
Realtek?
Monitor(s) Displays
Samsung S23B350
Screen Resolution
1920x1080
Hard Drives
WD Green 2TB (SATA), WD Green 3TB (SATA), WD Blue 4TB (SATA), WD Blue 6TB (SATA)