Thanks for this post. I could also overcome this same issue.
Issue was getting black blank page in spider post installation.
Then I just read this post, and did below command in Anaconda prompt. And then I launched spider, its worked as expected…Thanks a lot for this post.
(base) C:\Users\nice>conda install pyqt=5.6
Solving environment: done
Package Plan
environment location: C:\Users\nice\Anaconda3
added / updated specs:
- pyqt=5.6
The following packages will be downloaded:
package                    |            build
---------------------------|-----------------
qt-5.6.2                   |  vc14h6f8c307_12        55.8 MB
matplotlib-2.2.2           |   py37had4c4a9_2         6.5 MB
pyqt-5.6.0                 |   py37ha878b3d_6         4.5 MB
certifi-2018.10.15         |           py37_0         138 KB
qtconsole-4.4.2            |           py37_0         200 KB
sip-4.18.1                 |   py37h6538335_2         269 KB
------------------------------------------------------------
                                       Total:        67.5 MB

The following packages will be REMOVED:
anaconda:   5.3.0-py37_0

The following packages will be UPDATED:
certifi:    2018.8.24-py37_1      --> 2018.10.15-py37_0
qtconsole:  4.4.1-py37_0          --> 4.4.2-py37_0

The following packages will be DOWNGRADED:
matplotlib: 2.2.3-py37hd159220_0  --> 2.2.2-py37had4c4a9_2
pyqt:       5.9.2-py37h6538335_2  --> 5.6.0-py37ha878b3d_6
qt:         5.9.6-vc14h1e9a669_2  --> 5.6.2-vc14h6f8c307_12
sip:        4.19.8-py37h6538335_0 --> 4.18.1-py37h6538335_2

Proceed ([y]/n)? y
Downloading and Extracting Packages
qt-5.6.2             | 55.8 MB   | #################################### | 100%
matplotlib-2.2.2     | 6.5 MB    | #################################### | 100%
pyqt-5.6.0           | 4.5 MB    | #################################### | 100%
certifi-2018.10.15   | 138 KB    | #################################### | 100%
qtconsole-4.4.2      | 200 KB    | #################################### | 100%
sip-4.18.1           | 269 KB    | #################################### | 100%
Preparing transaction: done
Verifying transaction: done
Executing transaction: done
(base) C:\Users\nice>