Here's my system spec if needed.
Lightroom version: CC 2015.3 [ 1052427 ]
License: Creative Cloud
Operating system: Windows 10
Application architecture: x64
System architecture: x64
Logical processor count: 16
Processor speed: 3.0 GHz
Built-in memory: 32669.6 MB
Real memory available to Lightroom: 32669.6 MB
Real memory used by Lightroom: 3812.5 MB (11.6%)
Virtual memory used by Lightroom: 4231.4 MB
Memory cache size: 5572.3 MB
Maximum thread count used by Camera Raw: 16
Camera Raw SIMD optimization: SSE2,AVX,AVX2
System DPI setting: 144 DPI (high DPI mode)
Desktop composition enabled: Yes
Displays: 1) 3840x2160
Input types: Multitouch: No, Integrated touch: No, Integrated pen: No, External touch: No, External pen: No, Keyboard: No
Graphics Processor Info:
GeForce GTX 980 Ti/PCIe/SSE2
Check OpenGL support: Passed
Vendor: NVIDIA Corporation
Version: 3.3.0 NVIDIA 358.91
Renderer: GeForce GTX 980 Ti/PCIe/SSE2
LanguageVersion: 3.30 NVIDIA via Cg compiler
Application folder: C:\Program Files\Adobe\Adobe Lightroom
Library Path: S:\Lightroom\Lightroom Catalog.lrcat
Settings Folder: C:\Users\MikeyB\AppData\Roaming\Adobe\Lightroom
1) Canon Tether Plugin
4) Leica Tether Plugin
5) Nikon Tether Plugin
Config.lua flags: None
Adapter #1: Vendor : 10de
Device : 17c8
Subsystem : 854f1043
Revision : a1
Video Memory : 6048
Adapter #2: Vendor : 1414
Device : 8c
Subsystem : 0
Revision : 0
Video Memory : 0
AudioDeviceName: Line Out (3- Scarlett 2i2 USB)
GPUDevice: not available
Have a look at this thread and see if it helps.
With respect to the Sign Out / Sign In issue try using the Quit Lightroom option from the Lightroom menu bar.
Sign Out = Deactivate
Sign In = Activate
Thanks Per, I'll give that a try and see how I get on.
Thanks - I've tried the sign out and sign in options but don't want to do that everytime I open Lightroom.
If you use the quit option you should not have to Sign In the next time you start Lightroom.
Thanks for everyone who's taken their time to reply, much appreciated as this has been doing my head in for a few weeks.
What I have done - and everything is running smoothly again is, delete all the preferences, delete all the cache including any smart or 1:1 previews and it's now working as expected.
I'll keep this thread up to date if I get the problem again and I'll try narrow down the actual problem and solution but hopefully this may help somebody.
What do you mean all preferences?